From 363c5923f0c1fdbd336b297076d5b7d9a9ca7128 Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Tue, 15 May 2018 11:19:51 -0700
Subject: [PATCH 1/6] Remove unused options.json file.

---
 packages/babel-plugin-transform-runtime/src/options.json | 3 ---
 1 file changed, 3 deletions(-)
 delete mode 100644 packages/babel-plugin-transform-runtime/src/options.json

diff --git a/packages/babel-plugin-transform-runtime/src/options.json b/packages/babel-plugin-transform-runtime/src/options.json
deleted file mode 100644
index b987a67bba..0000000000
--- a/packages/babel-plugin-transform-runtime/src/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": ["transform-runtime", "transform-regenerator"]
-}

From ec8330870ef0aae1b834c8a250148edce14c091a Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Tue, 15 May 2018 12:43:12 -0700
Subject: [PATCH 2/6] Refactor the runtime build-dist script.

---
 packages/babel-runtime/package.json          |   1 +
 packages/babel-runtime/scripts/build-dist.js | 204 ++++++++-----------
 2 files changed, 88 insertions(+), 117 deletions(-)

diff --git a/packages/babel-runtime/package.json b/packages/babel-runtime/package.json
index 18098e06f9..aa44500199 100644
--- a/packages/babel-runtime/package.json
+++ b/packages/babel-runtime/package.json
@@ -13,6 +13,7 @@
     "@babel/core": "7.0.0-beta.55",
     "@babel/helpers": "7.0.0-beta.55",
     "@babel/plugin-transform-runtime": "7.0.0-beta.55",
+    "@babel/template": "7.0.0-beta.55",
     "@babel/preset-env": "7.0.0-beta.55",
     "@babel/types": "7.0.0-beta.55"
   }
diff --git a/packages/babel-runtime/scripts/build-dist.js b/packages/babel-runtime/scripts/build-dist.js
index 62aed66aa9..ff2d79dbaa 100644
--- a/packages/babel-runtime/scripts/build-dist.js
+++ b/packages/babel-runtime/scripts/build-dist.js
@@ -1,77 +1,112 @@
 "use strict";
 
+const path = require("path");
 const outputFile = require("output-file-sync");
-const coreDefinitions = require("@babel/plugin-transform-runtime").definitions;
 const helpers = require("@babel/helpers");
 const babel = require("@babel/core");
+const template = require("@babel/template");
 const t = require("@babel/types");
 
-const paths = ["is-iterable", "get-iterator"];
+const transformRuntime = require("@babel/plugin-transform-runtime");
+const corejs2Definitions = require("@babel/plugin-transform-runtime").definitions;
 
-Object.keys(coreDefinitions.builtins).forEach((key) => {
-  const path = coreDefinitions.builtins[key];
-  paths.push(path);
-});
+const runtimeRoot = path.resolve(__dirname, "..");
 
-Object.keys(coreDefinitions.methods).forEach((key) => {
-  const props = coreDefinitions.methods[key];
-  Object.keys(props).forEach((key2) => {
-    const path = props[key2];
+writeCoreJS2(runtimeRoot);
+
+writeHelpers(runtimeRoot, { esm: false, corejs2: false });
+writeHelpers(runtimeRoot, { esm: false, corejs2: true });
+writeHelpers(runtimeRoot, { esm: true, corejs2: false });
+writeHelpers(runtimeRoot, { esm: true, corejs2: true });
+
+function writeCoreJS2(pkgDirname) {
+  const paths = ["is-iterable", "get-iterator"];
+
+  Object.keys(corejs2Definitions.builtins).forEach(key => {
+    const path = corejs2Definitions.builtins[key];
     paths.push(path);
   });
-});
 
-paths.forEach(function(path) {
-  writeFile(
-    "core-js/" + path + ".js",
-    defaultify(`require("core-js/library/fn/${path}")`)
-  );
-});
+  Object.keys(corejs2Definitions.methods).forEach(key => {
+    const props = corejs2Definitions.methods[key];
+    Object.keys(props).forEach(key2 => {
+      paths.push(props[key2]);
+    });
+  });
 
-function relative(filename) {
-  return `${__dirname}/../${filename}`;
+  paths.forEach(function(corePath) {
+    outputFile(
+      path.join(pkgDirname, "core-js", `${corePath}.js`),
+      `module.exports = require("core-js/library/fn/${corePath}");`
+    );
+  });
 }
 
-function defaultify(name) {
-  return `module.exports = ${name};`;
-}
+function writeHelpers(pkgDirname, { esm, corejs2 }) {
+  for (const helperName of helpers.list) {
+    const helperFilename = path.join(
+      pkgDirname,
+      "helpers",
+      corejs2 ? "" : "builtin",
+      esm ? "es6" : "",
+      `${helperName}.js`
+    );
 
-function writeRootFile(filename, content) {
-  filename = relative(filename);
-  outputFile(filename, content);
-}
-
-function writeFile(filename, content) {
-  return writeRootFile(filename, content);
-}
-
-function makeTransformOpts(modules, useBuiltIns) {
-  const opts = {
-    presets: [[require("@babel/preset-env"), { modules: false }]],
-
-    plugins: [
-      [
-        require("@babel/plugin-transform-runtime"),
-        { useBuiltIns, useESModules: modules === false },
-      ],
-    ],
-  };
-  return opts;
-}
-
-function adjustImportPath(node, relativePath) {
-  if (helpers.list.indexOf(node.value) >= 0) {
-    node.value = `./${node.value}`;
-  } else {
-    node.value = node.value.replace(/^@babel\/runtime/, relativePath);
+    outputFile(
+      helperFilename,
+      buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 })
+    );
   }
 }
 
-function buildRuntimeRewritePlugin(relativePath, helperName, dependencies) {
+function buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 }) {
+  const tree = t.program([], [], esm ? "module" : "script");
+  const dependencies = {};
+  let bindings = null;
+
+  if (!esm) {
+    bindings = [];
+    for (const dep of helpers.getDependencies(helperName)) {
+      const id = (dependencies[dep] = t.identifier(t.toIdentifier(dep)));
+      tree.body.push(template.statement.ast`
+        var ${id} = require("${`./${dep}`}");
+      `);
+      bindings.push(id.name);
+    }
+  }
+
+  const helper = helpers.get(
+    helperName,
+    dep => dependencies[dep],
+    esm ? null : template.expression.ast`module.exports`,
+    bindings
+  );
+  tree.body.push(...helper.nodes);
+
+  return babel.transformFromAst(tree, null, {
+    presets: [[require("@babel/preset-env"), { modules: false }]],
+    plugins: [
+      [transformRuntime, { useBuiltIns: !corejs2, useESModules: esm }],
+      buildRuntimeRewritePlugin(
+        path.relative(path.dirname(helperFilename), pkgDirname),
+        helperName
+      ),
+    ],
+  }).code;
+}
+
+function buildRuntimeRewritePlugin(relativePath, helperName) {
+  function adjustImportPath(node, relativePath) {
+    node.value =
+      helpers.list.indexOf(node.value) !== -1
+        ? `./${node.value}`
+        : node.value.replace(/^@babel\/runtime/, relativePath);
+  }
+
   return {
     pre(file) {
       const original = file.get("helperGenerator");
-      file.set("helperGenerator", (name) => {
+      file.set("helperGenerator", name => {
         // make sure that helpers won't insert circular references to themselves
         if (name === helperName) return false;
 
@@ -98,68 +133,3 @@ function buildRuntimeRewritePlugin(relativePath, helperName, dependencies) {
     },
   };
 }
-
-function buildRequireCall(id, dep) {
-  return t.variableDeclaration("var", [
-    t.variableDeclarator(
-      id,
-      t.callExpression(t.identifier("require"), [t.stringLiteral(dep)])
-    )
-  ]);
-}
-
-function buildHelper(helperName, modules, useBuiltIns) {
-  const id =
-    modules === "commonjs"
-      ? t.memberExpression(t.identifier("module"), t.identifier("exports"))
-      : null;
-  const sourceType = modules === "commonjs" ? "script" : "module";
-
-  const tree = t.program([], [], sourceType);
-  const dependencies = {};
-  let bindings = null;
-
-  if (modules === "commonjs") {
-    bindings = [];
-    for (const dep of helpers.getDependencies(helperName)) {
-      const id = dependencies[dep] = t.identifier(t.toIdentifier(dep));
-      tree.body.push(buildRequireCall(id, dep));
-      bindings.push(id.name);
-    }
-  }
-
-  const helper = helpers.get(
-    helperName,
-    dep => dependencies[dep],
-    id,
-    bindings
-  );
-  tree.body.push.apply(tree.body, helper.nodes);
-
-  const transformOpts = makeTransformOpts(modules, useBuiltIns);
-
-  const relative = useBuiltIns ? "../.." : "..";
-  
-  return babel.transformFromAst(tree, null, {
-    presets: transformOpts.presets,
-    plugins: transformOpts.plugins.concat([
-      buildRuntimeRewritePlugin(
-        modules === false ? `../${relative}` : relative,
-        helperName
-      ),
-    ]),
-  }).code;
-}
-
-for (const modules of ["commonjs", false]) {
-  for (const builtin of [false, true]) {
-    const dirname = `helpers/${builtin ? "builtin/" : ""}${!modules ? "es6/" : ""}`;
-
-    for (const helperName of helpers.list) {
-      writeFile(
-        `${dirname}${helperName}.js`,
-        buildHelper(helperName, modules, builtin)
-      );
-    }
-  }
-}

From a149466001822ffda07bbf27f4462bf5ca778b74 Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Tue, 15 May 2018 12:55:33 -0700
Subject: [PATCH 3/6] Move build-dist script to the runtime transform.

---
 .eslintignore                                             | 2 +-
 Makefile                                                  | 4 ++--
 packages/babel-plugin-transform-runtime/.npmignore        | 1 +
 packages/babel-plugin-transform-runtime/package.json      | 7 ++++++-
 .../scripts/build-dist.js                                 | 6 +++---
 packages/babel-plugin-transform-runtime/src/index.js      | 2 --
 packages/babel-runtime/.npmignore                         | 1 -
 packages/babel-runtime/package.json                       | 8 --------
 8 files changed, 13 insertions(+), 18 deletions(-)
 rename packages/{babel-runtime => babel-plugin-transform-runtime}/scripts/build-dist.js (94%)

diff --git a/.eslintignore b/.eslintignore
index 4a10dadac2..c84198bb07 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -4,7 +4,7 @@
 package.json
 lerna.json
 packages/babel-runtime
-!packages/babel-runtime/scripts
+!packages/babel-plugin-transform-runtime/scripts
 !packages/babel-runtime/core-js.js
 packages/*/node_modules
 packages/*/lib
diff --git a/Makefile b/Makefile
index 2ed85e6bbb..0fba2cf04a 100644
--- a/Makefile
+++ b/Makefile
@@ -31,7 +31,7 @@ build-preset-env-standalone:
 build-dist: build
 	cd packages/babel-polyfill; \
 	scripts/build-dist.sh
-	cd packages/babel-runtime; \
+	cd packages/babel-plugin-transform-runtime; \
 	node scripts/build-dist.js
 
 watch: clean clean-lib
@@ -120,7 +120,7 @@ bootstrap: clean-all
 	yarn --ignore-engines
 	./node_modules/.bin/lerna bootstrap -- --ignore-engines
 	make build
-	cd packages/babel-runtime; \
+	cd packages/babel-plugin-transform-runtime; \
 	node scripts/build-dist.js
 
 clean-lib:
diff --git a/packages/babel-plugin-transform-runtime/.npmignore b/packages/babel-plugin-transform-runtime/.npmignore
index f980694583..57e1671459 100644
--- a/packages/babel-plugin-transform-runtime/.npmignore
+++ b/packages/babel-plugin-transform-runtime/.npmignore
@@ -1,3 +1,4 @@
+scripts
 src
 test
 *.log
diff --git a/packages/babel-plugin-transform-runtime/package.json b/packages/babel-plugin-transform-runtime/package.json
index 25e94b2d32..d0ef406110 100644
--- a/packages/babel-plugin-transform-runtime/package.json
+++ b/packages/babel-plugin-transform-runtime/package.json
@@ -17,6 +17,11 @@
   },
   "devDependencies": {
     "@babel/core": "7.0.0-beta.55",
-    "@babel/helper-plugin-test-runner": "7.0.0-beta.55"
+    "@babel/helpers": "7.0.0-beta.55",
+    "@babel/helper-plugin-test-runner": "7.0.0-beta.55",
+    "@babel/plugin-transform-runtime": "7.0.0-beta.55",
+    "@babel/template": "7.0.0-beta.55",
+    "@babel/preset-env": "7.0.0-beta.55",
+    "@babel/types": "7.0.0-beta.53"
   }
 }
diff --git a/packages/babel-runtime/scripts/build-dist.js b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
similarity index 94%
rename from packages/babel-runtime/scripts/build-dist.js
rename to packages/babel-plugin-transform-runtime/scripts/build-dist.js
index ff2d79dbaa..03e6aab853 100644
--- a/packages/babel-runtime/scripts/build-dist.js
+++ b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
@@ -7,10 +7,10 @@ const babel = require("@babel/core");
 const template = require("@babel/template");
 const t = require("@babel/types");
 
-const transformRuntime = require("@babel/plugin-transform-runtime");
-const corejs2Definitions = require("@babel/plugin-transform-runtime").definitions;
+const transformRuntime = require("../");
+const corejs2Definitions = require("../lib/definitions").default;
 
-const runtimeRoot = path.resolve(__dirname, "..");
+const runtimeRoot = path.resolve(__dirname, "..", "..", "babel-runtime");
 
 writeCoreJS2(runtimeRoot);
 
diff --git a/packages/babel-plugin-transform-runtime/src/index.js b/packages/babel-plugin-transform-runtime/src/index.js
index 876fea7641..546938be12 100644
--- a/packages/babel-plugin-transform-runtime/src/index.js
+++ b/packages/babel-plugin-transform-runtime/src/index.js
@@ -227,5 +227,3 @@ export default declare((api, options) => {
     },
   };
 });
-
-export { definitions };
diff --git a/packages/babel-runtime/.npmignore b/packages/babel-runtime/.npmignore
index 57e1671459..f980694583 100644
--- a/packages/babel-runtime/.npmignore
+++ b/packages/babel-runtime/.npmignore
@@ -1,4 +1,3 @@
-scripts
 src
 test
 *.log
diff --git a/packages/babel-runtime/package.json b/packages/babel-runtime/package.json
index aa44500199..79fc3de77f 100644
--- a/packages/babel-runtime/package.json
+++ b/packages/babel-runtime/package.json
@@ -8,13 +8,5 @@
   "dependencies": {
     "core-js": "^2.5.7",
     "regenerator-runtime": "^0.12.0"
-  },
-  "devDependencies": {
-    "@babel/core": "7.0.0-beta.55",
-    "@babel/helpers": "7.0.0-beta.55",
-    "@babel/plugin-transform-runtime": "7.0.0-beta.55",
-    "@babel/template": "7.0.0-beta.55",
-    "@babel/preset-env": "7.0.0-beta.55",
-    "@babel/types": "7.0.0-beta.55"
   }
 }

From 9c598a8e283790b7c5849862f4ad462cd2c17ba5 Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Tue, 15 May 2018 15:46:13 -0700
Subject: [PATCH 4/6] Build an explicit runtime.

---
 .../scripts/build-dist.js                     | 51 ++++++++++++++-----
 1 file changed, 39 insertions(+), 12 deletions(-)

diff --git a/packages/babel-plugin-transform-runtime/scripts/build-dist.js b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
index 03e6aab853..c06e621783 100644
--- a/packages/babel-plugin-transform-runtime/scripts/build-dist.js
+++ b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
@@ -10,16 +10,14 @@ const t = require("@babel/types");
 const transformRuntime = require("../");
 const corejs2Definitions = require("../lib/definitions").default;
 
-const runtimeRoot = path.resolve(__dirname, "..", "..", "babel-runtime");
+writeHelpers("@babel/runtime", { corejs2: false });
 
-writeCoreJS2(runtimeRoot);
+writeCoreJS2("@babel/runtime");
+writeHelpers("@babel/runtime", { corejs2: true });
 
-writeHelpers(runtimeRoot, { esm: false, corejs2: false });
-writeHelpers(runtimeRoot, { esm: false, corejs2: true });
-writeHelpers(runtimeRoot, { esm: true, corejs2: false });
-writeHelpers(runtimeRoot, { esm: true, corejs2: true });
+function writeCoreJS2(runtimeName) {
+  const pkgDirname = getRuntimeRoot(runtimeName);
 
-function writeCoreJS2(pkgDirname) {
   const paths = ["is-iterable", "get-iterator"];
 
   Object.keys(corejs2Definitions.builtins).forEach(key => {
@@ -42,7 +40,14 @@ function writeCoreJS2(pkgDirname) {
   });
 }
 
-function writeHelpers(pkgDirname, { esm, corejs2 }) {
+function writeHelpers(runtimeName, { corejs2 } = {}) {
+  writeHelperFiles(runtimeName, { corejs2, esm: false });
+  writeHelperFiles(runtimeName, { corejs2, esm: true });
+}
+
+function writeHelperFiles(runtimeName, { esm, corejs2 }) {
+  const pkgDirname = getRuntimeRoot(runtimeName);
+
   for (const helperName of helpers.list) {
     const helperFilename = path.join(
       pkgDirname,
@@ -54,12 +59,33 @@ function writeHelpers(pkgDirname, { esm, corejs2 }) {
 
     outputFile(
       helperFilename,
-      buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 })
+      buildHelper(
+        runtimeName,
+        pkgDirname,
+        helperFilename,
+        helperName,
+        { esm, corejs2 }
+      )
     );
   }
 }
 
-function buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 }) {
+function getRuntimeRoot(runtimeName) {
+  return path.resolve(
+    __dirname,
+    "..",
+    "..",
+    runtimeName.replace(/^@babel\//, "babel-")
+  );
+}
+
+function buildHelper(
+  runtimeName,
+  pkgDirname,
+  helperFilename,
+  helperName,
+  { esm, corejs2 }
+) {
   const tree = t.program([], [], esm ? "module" : "script");
   const dependencies = {};
   let bindings = null;
@@ -88,6 +114,7 @@ function buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 }) {
     plugins: [
       [transformRuntime, { useBuiltIns: !corejs2, useESModules: esm }],
       buildRuntimeRewritePlugin(
+        runtimeName,
         path.relative(path.dirname(helperFilename), pkgDirname),
         helperName
       ),
@@ -95,12 +122,12 @@ function buildHelper(pkgDirname, helperFilename, helperName, { esm, corejs2 }) {
   }).code;
 }
 
-function buildRuntimeRewritePlugin(relativePath, helperName) {
+function buildRuntimeRewritePlugin(runtimeName, relativePath, helperName) {
   function adjustImportPath(node, relativePath) {
     node.value =
       helpers.list.indexOf(node.value) !== -1
         ? `./${node.value}`
-        : node.value.replace(/^@babel\/runtime/, relativePath);
+        : node.value.replace(runtimeName, relativePath);
   }
 
   return {

From 3210a7a873d6aced7aa3313a8be5121d8c4e5072 Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Thu, 21 Jun 2018 20:55:19 -0700
Subject: [PATCH 5/6] Default to non-corejs helpers.

---
 .../interop-loose/imports-hoisting/output.js  |   4 +-
 .../interop-loose/multi-load/output.js        |   4 +-
 .../interop/imports-hoisting/output.js        |   4 +-
 .../fixtures/interop/multi-load/output.js     |   4 +-
 .../test/fixtures/regression/T7041/output.js  |   4 +-
 .../src/index.js                              | 101 +++++++++++++-----
 .../runtime/aliased-constructors/output.js    |  17 +--
 .../test/fixtures/runtime/catch-all/output.js |   4 +-
 .../test/fixtures/runtime/class/output.js     |   2 +-
 .../fixtures/runtime/custom-runtime/input.mjs |   9 --
 .../runtime/custom-runtime/options.json       |   3 -
 .../runtime/custom-runtime/output.mjs         |  24 -----
 .../fixtures/runtime/es6-for-of/output.js     |   4 +-
 .../test/fixtures/runtime/full/output.mjs     |   3 +-
 .../test/fixtures/runtime/modules/output.js   |  12 +--
 .../runtime/symbol-iterator-in/output.js      |   4 +-
 .../runtime/symbol-iterator/output.js         |   4 +-
 .../input.js                                  |   0
 .../corejsVersion-useES6Modules/options.json  |   3 +
 .../output.js                                 |   8 +-
 .../{useBuiltIns => corejsVersion}/input.js   |   0
 .../use-options/corejsVersion/options.json    |   3 +
 .../output.js                                 |   8 +-
 .../useBuiltIns-useESModules/options.json     |   3 -
 .../use-options/useBuiltIns/options.json      |   3 -
 .../use-options/useESModules/output.js        |   8 +-
 26 files changed, 113 insertions(+), 130 deletions(-)
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/input.mjs
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/options.json
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/output.mjs
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{useBuiltIns-useESModules => corejsVersion-useES6Modules}/input.js (100%)
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{useBuiltIns => corejsVersion-useES6Modules}/output.js (54%)
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{useBuiltIns => corejsVersion}/input.js (100%)
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{useBuiltIns-useESModules => corejsVersion}/output.js (53%)
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/options.json
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/options.json

diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
index d17f42975d..169a772325 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
@@ -1,8 +1,8 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
+var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
 
-var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/taggedTemplateLiteral"));
+var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/builtin/taggedTemplateLiteral"));
 
 function _templateObject() {
   const data = (0, _taggedTemplateLiteral2.default)(["foo"]);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
index 9930c38eb4..44fd33fe96 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
@@ -1,7 +1,7 @@
 "use strict";
 
-var _interopRequireDefault3 = require("@babel/runtime/helpers/interopRequireDefault");
+var _interopRequireDefault3 = require("@babel/runtime/helpers/builtin/interopRequireDefault");
 
-var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/interopRequireDefault"));
+var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/builtin/interopRequireDefault"));
 
 console.log(_interopRequireDefault2.default);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
index d17f42975d..169a772325 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
@@ -1,8 +1,8 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
+var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
 
-var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/taggedTemplateLiteral"));
+var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/builtin/taggedTemplateLiteral"));
 
 function _templateObject() {
   const data = (0, _taggedTemplateLiteral2.default)(["foo"]);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
index 9930c38eb4..44fd33fe96 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
@@ -1,7 +1,7 @@
 "use strict";
 
-var _interopRequireDefault3 = require("@babel/runtime/helpers/interopRequireDefault");
+var _interopRequireDefault3 = require("@babel/runtime/helpers/builtin/interopRequireDefault");
 
-var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/interopRequireDefault"));
+var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/builtin/interopRequireDefault"));
 
 console.log(_interopRequireDefault2.default);
diff --git a/packages/babel-plugin-transform-regenerator/test/fixtures/regression/T7041/output.js b/packages/babel-plugin-transform-regenerator/test/fixtures/regression/T7041/output.js
index d122e2c481..a67193cb03 100644
--- a/packages/babel-plugin-transform-regenerator/test/fixtures/regression/T7041/output.js
+++ b/packages/babel-plugin-transform-regenerator/test/fixtures/regression/T7041/output.js
@@ -1,12 +1,10 @@
 var _regeneratorRuntime = require("@babel/runtime/regenerator");
 
-var _Object$keys = require("@babel/runtime/core-js/object/keys");
-
 var _marked =
 /*#__PURE__*/
 _regeneratorRuntime.mark(fn);
 
-_Object$keys({});
+Object.keys({});
 
 function fn() {
   return _regeneratorRuntime.wrap(function fn$(_context) {
diff --git a/packages/babel-plugin-transform-runtime/src/index.js b/packages/babel-plugin-transform-runtime/src/index.js
index 546938be12..2d05cb918e 100644
--- a/packages/babel-plugin-transform-runtime/src/index.js
+++ b/packages/babel-plugin-transform-runtime/src/index.js
@@ -8,29 +8,82 @@ export default declare((api, options) => {
   api.assertVersion(7);
 
   const {
-    helpers,
-    moduleName = "@babel/runtime",
-    polyfill,
-    regenerator,
-    useBuiltIns,
-    useESModules,
+    corejsVersion = false,
+    helpers: useRuntimeHelpers = true,
+    regenerator: useRuntimeRegenerator = true,
+    useESModules = false,
     version: runtimeVersion = "7.0.0-beta.0",
   } = options;
-  const regeneratorEnabled = regenerator !== false;
-  const notPolyfillOrDoesUseBuiltIns = polyfill === false || useBuiltIns;
-  const isPolyfillAndUseBuiltIns = polyfill && useBuiltIns;
-  const baseHelpersDir = useBuiltIns ? "helpers/builtin" : "helpers";
-  const helpersDir = useESModules ? `${baseHelpersDir}/es6` : baseHelpersDir;
+
+  if (typeof useRuntimeRegenerator !== "boolean") {
+    throw new Error(
+      "The 'regenerator' option must be undefined, or a boolean.",
+    );
+  }
+  if (typeof useRuntimeHelpers !== "boolean") {
+    throw new Error("The 'helpers' option must be undefined, or a boolean.");
+  }
+  if (typeof useESModules !== "boolean") {
+    throw new Error(
+      "The 'useESModules' option must be undefined, or a boolean.",
+    );
+  }
+  if (
+    corejsVersion !== false &&
+    (typeof corejsVersion !== "number" || corejsVersion !== 2) &&
+    (typeof corejsVersion !== "string" || corejsVersion !== "2")
+  ) {
+    throw new Error(
+      `The 'corejsVersion' option must be undefined, false, or 2, or '2', ` +
+        `but got ${JSON.stringify(corejsVersion)}.`,
+    );
+  }
 
   function has(obj, key) {
     return Object.prototype.hasOwnProperty.call(obj, key);
   }
+  if (has(options, "useBuiltIns")) {
+    if (options.useBuiltIns) {
+      throw new Error(
+        "The 'useBuiltIns' option has been removed. The @babel/runtime " +
+          "module now uses builtins by default.",
+      );
+    } else {
+      throw new Error(
+        "The 'useBuiltIns' option has been removed. Use the 'corejsVersion'" +
+          "option with value '2' to polyfill with CoreJS 2.x via @babel/runtime.",
+      );
+    }
+  }
+  if (has(options, "polyfill")) {
+    if (options.polyfill === false) {
+      throw new Error(
+        "The 'polyfill' option has been removed. The @babel/runtime " +
+          "module now skips polyfilling by default.",
+      );
+    } else {
+      throw new Error(
+        "The 'polyfill' option has been removed. Use the 'corejsVersion'" +
+          "option with value '2' to polyfill with CoreJS 2.x via @babel/runtime.",
+      );
+    }
+  }
+  if (has(options, "moduleName")) {
+    throw new Error(
+      "The 'moduleName' option has been removed. @babel/transform-runtime " +
+        "no longer supports arbitrary runtimes.",
+    );
+  }
+
+  const helpersDir = useESModules ? "helpers/es6" : "helpers";
+  const injectCoreJS2 = `${corejsVersion}` === "2";
+  const moduleName = "@babel/runtime";
 
   const HEADER_HELPERS = ["interopRequireWildcard", "interopRequireDefault"];
 
   return {
     pre(file) {
-      if (helpers !== false) {
+      if (useRuntimeHelpers) {
         file.set("helperGenerator", name => {
           // If the helper didn't exist yet at the version given, we bail
           // out and let Babel either insert it directly, or throw an error
@@ -51,21 +104,13 @@ export default declare((api, options) => {
             isInteropHelper && !isModule(file.path) ? 4 : undefined;
 
           return this.addDefaultImport(
-            `${moduleName}/${helpersDir}/${name}`,
+            `${moduleName}/${helpersDir}/${injectCoreJS2 ? "" : "builtin/"}${name}`,
             name,
             blockHoist,
           );
         });
       }
 
-      if (isPolyfillAndUseBuiltIns) {
-        throw new Error(
-          "The polyfill option conflicts with useBuiltIns; use one or the other",
-        );
-      }
-
-      this.moduleName = moduleName;
-
       const cache = new Map();
 
       this.addDefaultImport = (source, nameHint, blockHoist) => {
@@ -94,17 +139,17 @@ export default declare((api, options) => {
     visitor: {
       ReferencedIdentifier(path) {
         const { node, parent, scope } = path;
-        if (node.name === "regeneratorRuntime" && regeneratorEnabled) {
+        if (node.name === "regeneratorRuntime" && useRuntimeRegenerator) {
           path.replaceWith(
             this.addDefaultImport(
-              `${this.moduleName}/regenerator`,
+              `${moduleName}/regenerator`,
               "regeneratorRuntime",
             ),
           );
           return;
         }
 
-        if (notPolyfillOrDoesUseBuiltIns) return;
+        if (!injectCoreJS2) return;
 
         if (t.isMemberExpression(parent)) return;
         if (!has(definitions.builtins, node.name)) return;
@@ -121,7 +166,7 @@ export default declare((api, options) => {
 
       // arr[Symbol.iterator]() -> _core.$for.getIterator(arr)
       CallExpression(path) {
-        if (notPolyfillOrDoesUseBuiltIns) return;
+        if (!injectCoreJS2) return;
 
         // we can't compile this
         if (path.node.arguments.length) return;
@@ -146,7 +191,7 @@ export default declare((api, options) => {
 
       // Symbol.iterator in arr -> core.$for.isIterable(arr)
       BinaryExpression(path) {
-        if (notPolyfillOrDoesUseBuiltIns) return;
+        if (!injectCoreJS2) return;
 
         if (path.node.operator !== "in") return;
         if (!path.get("left").matchesPattern("Symbol.iterator")) return;
@@ -165,7 +210,7 @@ export default declare((api, options) => {
       // Array.from -> _core.Array.from
       MemberExpression: {
         enter(path) {
-          if (notPolyfillOrDoesUseBuiltIns) return;
+          if (!injectCoreJS2) return;
           if (!path.isReferenced()) return;
 
           const { node } = path;
@@ -203,7 +248,7 @@ export default declare((api, options) => {
         },
 
         exit(path) {
-          if (notPolyfillOrDoesUseBuiltIns) return;
+          if (!injectCoreJS2) return;
           if (!path.isReferenced()) return;
 
           const { node } = path;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/aliased-constructors/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/aliased-constructors/output.js
index a7cfe5735c..70099860ad 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/aliased-constructors/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/aliased-constructors/output.js
@@ -1,14 +1,5 @@
-var _Map = require("@babel/runtime/core-js/map");
-
-var _Symbol = require("@babel/runtime/core-js/symbol");
-
-var _Promise = require("@babel/runtime/core-js/promise");
-
 obj.constructor === Object;
-obj.constructor === _Promise;
-
-_Symbol();
-
-_Symbol("test");
-
-new _Map();
+obj.constructor === Promise;
+Symbol();
+Symbol("test");
+new Map();
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/catch-all/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/catch-all/output.js
index c3a34c2503..8e9b315294 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/catch-all/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/catch-all/output.js
@@ -1,3 +1 @@
-var _Promise = require("@babel/runtime/core-js/promise");
-
-_Promise.resolve;
+Promise.resolve;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
index 60d3e2fb72..b5e3ecf4ad 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
@@ -1,4 +1,4 @@
-var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/builtin/classCallCheck");
 
 let Foo = function Foo() {
   "use strict";
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/input.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/input.mjs
deleted file mode 100644
index 0340999129..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/input.mjs
+++ /dev/null
@@ -1,9 +0,0 @@
-import foo, * as bar from "someModule";
-
-export const myWord = Symbol("abc");
-export function* giveWord () {
-  yield myWord;
-}
-
-foo;
-bar;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/options.json
deleted file mode 100644
index d8a7d30b95..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": [["transform-runtime", { "moduleName": "foo" }], "transform-regenerator"]
-}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/output.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/output.mjs
deleted file mode 100644
index 656dd6d030..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/custom-runtime/output.mjs
+++ /dev/null
@@ -1,24 +0,0 @@
-import _regeneratorRuntime from "foo/regenerator";
-import _Symbol from "foo/core-js/symbol";
-
-var _marked =
-/*#__PURE__*/
-_regeneratorRuntime.mark(giveWord);
-
-import foo, * as bar from "someModule";
-export const myWord = _Symbol("abc");
-export function giveWord() {
-  return _regeneratorRuntime.wrap(function giveWord$(_context) {
-    while (1) switch (_context.prev = _context.next) {
-      case 0:
-        _context.next = 2;
-        return myWord;
-
-      case 2:
-      case "end":
-        return _context.stop();
-    }
-  }, _marked, this);
-}
-foo;
-bar;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/es6-for-of/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/es6-for-of/output.js
index 0087e226c0..ec97a710ae 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/es6-for-of/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/es6-for-of/output.js
@@ -1,11 +1,9 @@
-var _getIterator = require("@babel/runtime/core-js/get-iterator");
-
 var _iteratorNormalCompletion = true;
 var _didIteratorError = false;
 var _iteratorError = undefined;
 
 try {
-  for (var _iterator = _getIterator(arr), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+  for (var _iterator = arr[Symbol.iterator](), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
     var i = _step.value;
   }
 } catch (err) {
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/full/output.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/full/output.mjs
index 3442c14425..7fe64e68c7 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/full/output.mjs
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/full/output.mjs
@@ -1,12 +1,11 @@
 import _regeneratorRuntime from "@babel/runtime/regenerator";
-import _Symbol from "@babel/runtime/core-js/symbol";
 
 var _marked =
 /*#__PURE__*/
 _regeneratorRuntime.mark(giveWord);
 
 import foo, * as bar from "someModule";
-export const myWord = _Symbol("abc");
+export const myWord = Symbol("abc");
 export function giveWord() {
   return _regeneratorRuntime.wrap(function giveWord$(_context) {
     while (1) switch (_context.prev = _context.next) {
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
index 3bfab64ad9..ba3228c9cf 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
@@ -1,10 +1,6 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
-
-var _Object$defineProperty = require("@babel/runtime/core-js/object/define-property");
-
-var _Object$keys = require("@babel/runtime/core-js/object/keys");
+var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
 
 Object.defineProperty(exports, "__esModule", {
   value: true
@@ -14,15 +10,13 @@ var _bar = _interopRequireDefault(require("bar"));
 
 var _mod = require("mod");
 
-_Object$keys(_mod).forEach(function (key) {
+Object.keys(_mod).forEach(function (key) {
   if (key === "default" || key === "__esModule") return;
-
-  _Object$defineProperty(exports, key, {
+  Object.defineProperty(exports, key, {
     enumerable: true,
     get: function () {
       return _mod[key];
     }
   });
 });
-
 _bar.default;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator-in/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator-in/output.js
index e4e3264bb5..49e71aa52d 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator-in/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator-in/output.js
@@ -1,3 +1 @@
-var _isIterable = require("@babel/runtime/core-js/is-iterable");
-
-_isIterable(Object(arr));
+Symbol.iterator in Object(arr);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator/output.js
index 22731130e8..ae1f0b9df5 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/symbol-iterator/output.js
@@ -1,3 +1 @@
-var _Symbol$iterator = require("@babel/runtime/core-js/symbol/iterator");
-
-_Symbol$iterator;
+Symbol.iterator;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/input.js
similarity index 100%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/input.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/input.js
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
new file mode 100644
index 0000000000..1057edde11
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejsVersion": 2, "useESModules": true }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
similarity index 54%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/output.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
index 0dcb1a6dc1..9d1599d1f2 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
@@ -1,10 +1,10 @@
-var _classCallCheck = require("@babel/runtime/helpers/builtin/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/es6/classCallCheck");
 
-var _possibleConstructorReturn = require("@babel/runtime/helpers/builtin/possibleConstructorReturn");
+var _possibleConstructorReturn = require("@babel/runtime/helpers/es6/possibleConstructorReturn");
 
-var _getPrototypeOf = require("@babel/runtime/helpers/builtin/getPrototypeOf");
+var _getPrototypeOf = require("@babel/runtime/helpers/es6/getPrototypeOf");
 
-var _inherits = require("@babel/runtime/helpers/builtin/inherits");
+var _inherits = require("@babel/runtime/helpers/es6/inherits");
 
 let Foo =
 /*#__PURE__*/
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/input.js
similarity index 100%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/input.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/input.js
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
new file mode 100644
index 0000000000..b5668b025a
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejsVersion": 2 }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
similarity index 53%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/output.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
index d5ad90a1c2..39882dcd46 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
@@ -1,10 +1,10 @@
-var _classCallCheck = require("@babel/runtime/helpers/builtin/es6/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
 
-var _possibleConstructorReturn = require("@babel/runtime/helpers/builtin/es6/possibleConstructorReturn");
+var _possibleConstructorReturn = require("@babel/runtime/helpers/possibleConstructorReturn");
 
-var _getPrototypeOf = require("@babel/runtime/helpers/builtin/es6/getPrototypeOf");
+var _getPrototypeOf = require("@babel/runtime/helpers/getPrototypeOf");
 
-var _inherits = require("@babel/runtime/helpers/builtin/es6/inherits");
+var _inherits = require("@babel/runtime/helpers/inherits");
 
 let Foo =
 /*#__PURE__*/
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/options.json
deleted file mode 100644
index ad048c74b1..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns-useESModules/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": [["transform-runtime", { "useBuiltIns": true, "useESModules": true }], "transform-classes"]
-}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/options.json
deleted file mode 100644
index a24c715714..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useBuiltIns/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": [["transform-runtime", { "useBuiltIns": true }], "transform-classes"]
-}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
index 9d1599d1f2..889a5a8d73 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
@@ -1,10 +1,10 @@
-var _classCallCheck = require("@babel/runtime/helpers/es6/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/es6/builtin/classCallCheck");
 
-var _possibleConstructorReturn = require("@babel/runtime/helpers/es6/possibleConstructorReturn");
+var _possibleConstructorReturn = require("@babel/runtime/helpers/es6/builtin/possibleConstructorReturn");
 
-var _getPrototypeOf = require("@babel/runtime/helpers/es6/getPrototypeOf");
+var _getPrototypeOf = require("@babel/runtime/helpers/es6/builtin/getPrototypeOf");
 
-var _inherits = require("@babel/runtime/helpers/es6/inherits");
+var _inherits = require("@babel/runtime/helpers/es6/builtin/inherits");
 
 let Foo =
 /*#__PURE__*/

From a8224d40e2ff5d2ef92152e4853257596d8097bc Mon Sep 17 00:00:00 2001
From: Logan Smyth <loganfsmyth@gmail.com>
Date: Sun, 24 Jun 2018 10:50:26 -0700
Subject: [PATCH 6/6] Split @babel/runtime into two separate runtime modules.

---
 .eslintignore                                 |  3 +-
 .gitignore                                    | 31 +++++++++--------
 Makefile                                      |  3 +-
 .../interop-loose/imports-hoisting/output.js  |  4 +--
 .../interop-loose/multi-load/output.js        |  4 +--
 .../interop/imports-hoisting/output.js        |  4 +--
 .../fixtures/interop/multi-load/output.js     |  4 +--
 .../scripts/build-dist.js                     | 34 ++++++++-----------
 .../src/index.js                              | 16 +++++----
 .../aliased-constructors/input.js             |  7 ++++
 .../aliased-constructors/options.json         |  3 ++
 .../aliased-constructors/output.js            | 14 ++++++++
 .../runtime-corejs2/catch-all/input.js        |  1 +
 .../runtime-corejs2/catch-all/options.json    |  3 ++
 .../runtime-corejs2/catch-all/output.js       |  3 ++
 .../fixtures/runtime-corejs2/class/input.js   |  1 +
 .../runtime-corejs2/class/options.json        |  3 ++
 .../fixtures/runtime-corejs2/class/output.js  |  7 ++++
 .../runtime-corejs2/es6-for-of/input.js       |  3 ++
 .../runtime-corejs2/es6-for-of/options.json   |  3 ++
 .../runtime-corejs2/es6-for-of/output.js      | 24 +++++++++++++
 .../fixtures/runtime-corejs2/full/input.mjs   |  9 +++++
 .../runtime-corejs2/full/options.json         |  3 ++
 .../fixtures/runtime-corejs2/full/output.mjs  | 24 +++++++++++++
 .../runtime-corejs2/modules-helpers/input.mjs |  5 +++
 .../modules-helpers/options.json              |  7 ++++
 .../runtime-corejs2/modules-helpers/output.js | 23 +++++++++++++
 .../runtime-corejs2/modules/input.mjs         |  4 +++
 .../runtime-corejs2/modules/options.json      |  3 ++
 .../runtime-corejs2/modules/output.js         | 28 +++++++++++++++
 .../runtime-corejs2/no-helpers/input.js       |  1 +
 .../runtime-corejs2/no-helpers/options.json   |  3 ++
 .../runtime-corejs2/no-helpers/output.js      |  7 ++++
 .../regenerator-runtime/input.js              |  2 ++
 .../regenerator-runtime/options.json          |  3 ++
 .../regenerator-runtime/output.js             | 13 +++++++
 .../symbol-iterator-in/input.js               |  1 +
 .../symbol-iterator-in/options.json           |  6 ++++
 .../symbol-iterator-in/output.js              |  3 ++
 .../runtime-corejs2/symbol-iterator/input.js  |  1 +
 .../symbol-iterator/options.json              |  3 ++
 .../runtime-corejs2/symbol-iterator/output.js |  3 ++
 .../test/fixtures/runtime/class/output.js     |  2 +-
 .../test/fixtures/runtime/modules/output.js   |  2 +-
 .../input.js                                  |  0
 .../corejs-useES6Modules/options.json         |  3 ++
 .../corejs-useES6Modules/output.js            | 23 +++++++++++++
 .../{corejsVersion => corejs}/input.js        |  0
 .../fixtures/use-options/corejs/options.json  |  3 ++
 .../fixtures/use-options/corejs/output.js     | 23 +++++++++++++
 .../corejsVersion-useES6Modules/options.json  |  3 --
 .../corejsVersion-useES6Modules/output.js     | 23 -------------
 .../use-options/corejsVersion/options.json    |  3 --
 .../use-options/corejsVersion/output.js       | 23 -------------
 .../use-options/useESModules/output.js        |  8 ++---
 packages/babel-runtime-corejs2/.npmignore     |  3 ++
 packages/babel-runtime-corejs2/README.md      | 19 +++++++++++
 .../core-js/map.js                            |  0
 .../helpers/esm}/iterableToArray.js           |  0
 .../helpers/esm}/temporalRef.js               |  0
 .../helpers/esm}/toArray.js                   |  0
 .../helpers/iterableToArray.js                |  9 +++++
 .../helpers}/temporalRef.js                   |  0
 .../helpers}/toArray.js                       |  0
 packages/babel-runtime-corejs2/package.json   | 12 +++++++
 .../regenerator/index.js                      |  1 +
 packages/babel-runtime/README.md              |  2 +-
 packages/babel-runtime/core-js.js             |  1 -
 .../helpers/builtin/iterableToArray.js        |  5 ---
 .../{builtin/es6 => esm}/iterableToArray.js   |  0
 .../helpers/{es6 => esm}/temporalRef.js       |  0
 .../helpers/{es6 => esm}/toArray.js           |  0
 .../babel-runtime/helpers/iterableToArray.js  |  6 +---
 packages/babel-runtime/package.json           |  3 +-
 74 files changed, 382 insertions(+), 122 deletions(-)
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/input.mjs
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/output.mjs
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/input.mjs
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/input.mjs
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/output.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/input.js
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/output.js
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{corejsVersion-useES6Modules => corejs-useES6Modules}/input.js (100%)
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/output.js
 rename packages/babel-plugin-transform-runtime/test/fixtures/use-options/{corejsVersion => corejs}/input.js (100%)
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/options.json
 create mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/output.js
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
 delete mode 100644 packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
 create mode 100644 packages/babel-runtime-corejs2/.npmignore
 create mode 100644 packages/babel-runtime-corejs2/README.md
 rename packages/{babel-runtime => babel-runtime-corejs2}/core-js/map.js (100%)
 rename packages/{babel-runtime/helpers/es6 => babel-runtime-corejs2/helpers/esm}/iterableToArray.js (100%)
 rename packages/{babel-runtime/helpers/builtin/es6 => babel-runtime-corejs2/helpers/esm}/temporalRef.js (100%)
 rename packages/{babel-runtime/helpers/builtin/es6 => babel-runtime-corejs2/helpers/esm}/toArray.js (100%)
 create mode 100644 packages/babel-runtime-corejs2/helpers/iterableToArray.js
 rename packages/{babel-runtime/helpers/builtin => babel-runtime-corejs2/helpers}/temporalRef.js (100%)
 rename packages/{babel-runtime/helpers/builtin => babel-runtime-corejs2/helpers}/toArray.js (100%)
 create mode 100644 packages/babel-runtime-corejs2/package.json
 create mode 100644 packages/babel-runtime-corejs2/regenerator/index.js
 delete mode 100644 packages/babel-runtime/core-js.js
 delete mode 100644 packages/babel-runtime/helpers/builtin/iterableToArray.js
 rename packages/babel-runtime/helpers/{builtin/es6 => esm}/iterableToArray.js (100%)
 rename packages/babel-runtime/helpers/{es6 => esm}/temporalRef.js (100%)
 rename packages/babel-runtime/helpers/{es6 => esm}/toArray.js (100%)

diff --git a/.eslintignore b/.eslintignore
index c84198bb07..18e74eafba 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -5,7 +5,8 @@ package.json
 lerna.json
 packages/babel-runtime
 !packages/babel-plugin-transform-runtime/scripts
-!packages/babel-runtime/core-js.js
+!packages/babel-runtime-corejs2/core-js.js
+packages/babel-runtime-corejs2
 packages/*/node_modules
 packages/*/lib
 packages/*/dist
diff --git a/.gitignore b/.gitignore
index a2f346175f..500e46cd8c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,24 +12,27 @@ coverage
 dist
 /.package.json
 package-lock.json
-/packages/babel-runtime/core-js/**/*.js
-!/packages/babel-runtime/core-js/map.js
+
 /packages/babel-runtime/helpers/*.js
 !/packages/babel-runtime/helpers/toArray.js
 !/packages/babel-runtime/helpers/iterableToArray.js
 !/packages/babel-runtime/helpers/temporalRef.js
-/packages/babel-runtime/helpers/builtin/*.js
-!/packages/babel-runtime/helpers/builtin/toArray.js
-!/packages/babel-runtime/helpers/builtin/iterableToArray.js
-!/packages/babel-runtime/helpers/builtin/temporalRef.js
-/packages/babel-runtime/helpers/builtin/es6/*.js
-!/packages/babel-runtime/helpers/builtin/es6/toArray.js
-!/packages/babel-runtime/helpers/builtin/es6/iterableToArray.js
-!/packages/babel-runtime/helpers/builtin/es6/temporalRef.js
-/packages/babel-runtime/helpers/es6/*.js
-!/packages/babel-runtime/helpers/es6/toArray.js
-!/packages/babel-runtime/helpers/es6/iterableToArray.js
-!/packages/babel-runtime/helpers/es6/temporalRef.js
+/packages/babel-runtime/helpers/esm/*.js
+!/packages/babel-runtime/helpers/esm/toArray.js
+!/packages/babel-runtime/helpers/esm/iterableToArray.js
+!/packages/babel-runtime/helpers/esm/temporalRef.js
+
+/packages/babel-runtime-corejs2/helpers/*.js
+!/packages/babel-runtime-corejs2/helpers/toArray.js
+!/packages/babel-runtime-corejs2/helpers/iterableToArray.js
+!/packages/babel-runtime-corejs2/helpers/temporalRef.js
+/packages/babel-runtime-corejs2/helpers/esm/*.js
+!/packages/babel-runtime-corejs2/helpers/esm/toArray.js
+!/packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js
+!/packages/babel-runtime-corejs2/helpers/esm/temporalRef.js
+/packages/babel-runtime-corejs2/core-js/**/*.js
+!/packages/babel-runtime-corejs2/core-js/map.js
+
 /packages/babel-register/test/.babel
 /packages/babel-cli/test/tmp
 /packages/babel-node/test/tmp
diff --git a/Makefile b/Makefile
index 0fba2cf04a..b0ec3ca0e2 100644
--- a/Makefile
+++ b/Makefile
@@ -108,7 +108,8 @@ publish:
 	git pull --rebase
 	make clean-lib
 	rm -rf packages/babel-runtime/helpers
-	rm -rf packages/babel-runtime/core-js
+	rm -rf packages/babel-runtime-corejs2/helpers
+	rm -rf packages/babel-runtime-corejs2/core-js
 	BABEL_ENV=production make build-dist
 	make test
 	# not using lerna independent mode atm, so only update packages that have changed since we use ^
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
index 169a772325..d17f42975d 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/imports-hoisting/output.js
@@ -1,8 +1,8 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
 
-var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/builtin/taggedTemplateLiteral"));
+var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/taggedTemplateLiteral"));
 
 function _templateObject() {
   const data = (0, _taggedTemplateLiteral2.default)(["foo"]);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
index 44fd33fe96..9930c38eb4 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop-loose/multi-load/output.js
@@ -1,7 +1,7 @@
 "use strict";
 
-var _interopRequireDefault3 = require("@babel/runtime/helpers/builtin/interopRequireDefault");
+var _interopRequireDefault3 = require("@babel/runtime/helpers/interopRequireDefault");
 
-var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/builtin/interopRequireDefault"));
+var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/interopRequireDefault"));
 
 console.log(_interopRequireDefault2.default);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
index 169a772325..d17f42975d 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/imports-hoisting/output.js
@@ -1,8 +1,8 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
 
-var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/builtin/taggedTemplateLiteral"));
+var _taggedTemplateLiteral2 = _interopRequireDefault(require("@babel/runtime/helpers/taggedTemplateLiteral"));
 
 function _templateObject() {
   const data = (0, _taggedTemplateLiteral2.default)(["foo"]);
diff --git a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
index 44fd33fe96..9930c38eb4 100644
--- a/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
+++ b/packages/babel-plugin-transform-modules-commonjs/test/fixtures/interop/multi-load/output.js
@@ -1,7 +1,7 @@
 "use strict";
 
-var _interopRequireDefault3 = require("@babel/runtime/helpers/builtin/interopRequireDefault");
+var _interopRequireDefault3 = require("@babel/runtime/helpers/interopRequireDefault");
 
-var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/builtin/interopRequireDefault"));
+var _interopRequireDefault2 = _interopRequireDefault3(require("@babel/runtime/helpers/interopRequireDefault"));
 
 console.log(_interopRequireDefault2.default);
diff --git a/packages/babel-plugin-transform-runtime/scripts/build-dist.js b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
index c06e621783..9381e3b962 100644
--- a/packages/babel-plugin-transform-runtime/scripts/build-dist.js
+++ b/packages/babel-plugin-transform-runtime/scripts/build-dist.js
@@ -10,10 +10,10 @@ const t = require("@babel/types");
 const transformRuntime = require("../");
 const corejs2Definitions = require("../lib/definitions").default;
 
-writeHelpers("@babel/runtime", { corejs2: false });
+writeHelpers("@babel/runtime");
 
-writeCoreJS2("@babel/runtime");
-writeHelpers("@babel/runtime", { corejs2: true });
+writeCoreJS2("@babel/runtime-corejs2");
+writeHelpers("@babel/runtime-corejs2", { corejs: 2 });
 
 function writeCoreJS2(runtimeName) {
   const pkgDirname = getRuntimeRoot(runtimeName);
@@ -40,32 +40,28 @@ function writeCoreJS2(runtimeName) {
   });
 }
 
-function writeHelpers(runtimeName, { corejs2 } = {}) {
-  writeHelperFiles(runtimeName, { corejs2, esm: false });
-  writeHelperFiles(runtimeName, { corejs2, esm: true });
+function writeHelpers(runtimeName, { corejs } = {}) {
+  writeHelperFiles(runtimeName, { corejs, esm: false });
+  writeHelperFiles(runtimeName, { corejs, esm: true });
 }
 
-function writeHelperFiles(runtimeName, { esm, corejs2 }) {
+function writeHelperFiles(runtimeName, { esm, corejs }) {
   const pkgDirname = getRuntimeRoot(runtimeName);
 
   for (const helperName of helpers.list) {
     const helperFilename = path.join(
       pkgDirname,
       "helpers",
-      corejs2 ? "" : "builtin",
-      esm ? "es6" : "",
+      esm ? "esm" : "",
       `${helperName}.js`
     );
 
     outputFile(
       helperFilename,
-      buildHelper(
-        runtimeName,
-        pkgDirname,
-        helperFilename,
-        helperName,
-        { esm, corejs2 }
-      )
+      buildHelper(runtimeName, pkgDirname, helperFilename, helperName, {
+        esm,
+        corejs,
+      })
     );
   }
 }
@@ -84,7 +80,7 @@ function buildHelper(
   pkgDirname,
   helperFilename,
   helperName,
-  { esm, corejs2 }
+  { esm, corejs }
 ) {
   const tree = t.program([], [], esm ? "module" : "script");
   const dependencies = {};
@@ -112,7 +108,7 @@ function buildHelper(
   return babel.transformFromAst(tree, null, {
     presets: [[require("@babel/preset-env"), { modules: false }]],
     plugins: [
-      [transformRuntime, { useBuiltIns: !corejs2, useESModules: esm }],
+      [transformRuntime, { corejs, useESModules: esm }],
       buildRuntimeRewritePlugin(
         runtimeName,
         path.relative(path.dirname(helperFilename), pkgDirname),
@@ -127,7 +123,7 @@ function buildRuntimeRewritePlugin(runtimeName, relativePath, helperName) {
     node.value =
       helpers.list.indexOf(node.value) !== -1
         ? `./${node.value}`
-        : node.value.replace(runtimeName, relativePath);
+        : node.value.replace(runtimeName + "/", relativePath + "/");
   }
 
   return {
diff --git a/packages/babel-plugin-transform-runtime/src/index.js b/packages/babel-plugin-transform-runtime/src/index.js
index 2d05cb918e..0e0f616afd 100644
--- a/packages/babel-plugin-transform-runtime/src/index.js
+++ b/packages/babel-plugin-transform-runtime/src/index.js
@@ -8,7 +8,7 @@ export default declare((api, options) => {
   api.assertVersion(7);
 
   const {
-    corejsVersion = false,
+    corejs: corejsVersion = false,
     helpers: useRuntimeHelpers = true,
     regenerator: useRuntimeRegenerator = true,
     useESModules = false,
@@ -34,7 +34,7 @@ export default declare((api, options) => {
     (typeof corejsVersion !== "string" || corejsVersion !== "2")
   ) {
     throw new Error(
-      `The 'corejsVersion' option must be undefined, false, or 2, or '2', ` +
+      `The 'corejs' option must be undefined, false, or 2, or '2', ` +
         `but got ${JSON.stringify(corejsVersion)}.`,
     );
   }
@@ -50,7 +50,7 @@ export default declare((api, options) => {
       );
     } else {
       throw new Error(
-        "The 'useBuiltIns' option has been removed. Use the 'corejsVersion'" +
+        "The 'useBuiltIns' option has been removed. Use the 'corejs'" +
           "option with value '2' to polyfill with CoreJS 2.x via @babel/runtime.",
       );
     }
@@ -63,7 +63,7 @@ export default declare((api, options) => {
       );
     } else {
       throw new Error(
-        "The 'polyfill' option has been removed. Use the 'corejsVersion'" +
+        "The 'polyfill' option has been removed. Use the 'corejs'" +
           "option with value '2' to polyfill with CoreJS 2.x via @babel/runtime.",
       );
     }
@@ -75,9 +75,11 @@ export default declare((api, options) => {
     );
   }
 
-  const helpersDir = useESModules ? "helpers/es6" : "helpers";
+  const helpersDir = useESModules ? "helpers/esm" : "helpers";
   const injectCoreJS2 = `${corejsVersion}` === "2";
-  const moduleName = "@babel/runtime";
+  const moduleName = injectCoreJS2
+    ? "@babel/runtime-corejs2"
+    : "@babel/runtime";
 
   const HEADER_HELPERS = ["interopRequireWildcard", "interopRequireDefault"];
 
@@ -104,7 +106,7 @@ export default declare((api, options) => {
             isInteropHelper && !isModule(file.path) ? 4 : undefined;
 
           return this.addDefaultImport(
-            `${moduleName}/${helpersDir}/${injectCoreJS2 ? "" : "builtin/"}${name}`,
+            `${moduleName}/${helpersDir}/${name}`,
             name,
             blockHoist,
           );
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/input.js
new file mode 100644
index 0000000000..b7c61b92b0
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/input.js
@@ -0,0 +1,7 @@
+obj.constructor === Object;
+obj.constructor === Promise;
+
+Symbol();
+Symbol("test");
+
+new Map();
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/options.json
new file mode 100644
index 0000000000..5c04c77630
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/output.js
new file mode 100644
index 0000000000..4e753ff15d
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/aliased-constructors/output.js
@@ -0,0 +1,14 @@
+var _Map = require("@babel/runtime-corejs2/core-js/map");
+
+var _Symbol = require("@babel/runtime-corejs2/core-js/symbol");
+
+var _Promise = require("@babel/runtime-corejs2/core-js/promise");
+
+obj.constructor === Object;
+obj.constructor === _Promise;
+
+_Symbol();
+
+_Symbol("test");
+
+new _Map();
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/input.js
new file mode 100644
index 0000000000..8e9b315294
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/input.js
@@ -0,0 +1 @@
+Promise.resolve;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/options.json
new file mode 100644
index 0000000000..5c04c77630
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/output.js
new file mode 100644
index 0000000000..de4a16bd91
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/catch-all/output.js
@@ -0,0 +1,3 @@
+var _Promise = require("@babel/runtime-corejs2/core-js/promise");
+
+_Promise.resolve;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/input.js
new file mode 100644
index 0000000000..4e6a6de653
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/input.js
@@ -0,0 +1 @@
+class Foo {}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/options.json
new file mode 100644
index 0000000000..2972db7d1a
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/output.js
new file mode 100644
index 0000000000..132a249e97
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/class/output.js
@@ -0,0 +1,7 @@
+var _classCallCheck = require("@babel/runtime-corejs2/helpers/classCallCheck");
+
+let Foo = function Foo() {
+  "use strict";
+
+  _classCallCheck(this, Foo);
+};
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/input.js
new file mode 100644
index 0000000000..48e5f59b2c
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/input.js
@@ -0,0 +1,3 @@
+for (var i of arr) {
+
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/options.json
new file mode 100644
index 0000000000..5b5b7b35f1
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": ["transform-for-of", ["transform-runtime", { "corejs": 2 }]]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/output.js
new file mode 100644
index 0000000000..be11791731
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/es6-for-of/output.js
@@ -0,0 +1,24 @@
+var _getIterator = require("@babel/runtime-corejs2/core-js/get-iterator");
+
+var _iteratorNormalCompletion = true;
+var _didIteratorError = false;
+var _iteratorError = undefined;
+
+try {
+  for (var _iterator = _getIterator(arr), _step; !(_iteratorNormalCompletion = (_step = _iterator.next()).done); _iteratorNormalCompletion = true) {
+    var i = _step.value;
+  }
+} catch (err) {
+  _didIteratorError = true;
+  _iteratorError = err;
+} finally {
+  try {
+    if (!_iteratorNormalCompletion && _iterator.return != null) {
+      _iterator.return();
+    }
+  } finally {
+    if (_didIteratorError) {
+      throw _iteratorError;
+    }
+  }
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/input.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/input.mjs
new file mode 100644
index 0000000000..0340999129
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/input.mjs
@@ -0,0 +1,9 @@
+import foo, * as bar from "someModule";
+
+export const myWord = Symbol("abc");
+export function* giveWord () {
+  yield myWord;
+}
+
+foo;
+bar;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/options.json
new file mode 100644
index 0000000000..5c04c77630
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/output.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/output.mjs
new file mode 100644
index 0000000000..bb91155014
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/full/output.mjs
@@ -0,0 +1,24 @@
+import _regeneratorRuntime from "@babel/runtime-corejs2/regenerator";
+import _Symbol from "@babel/runtime-corejs2/core-js/symbol";
+
+var _marked =
+/*#__PURE__*/
+_regeneratorRuntime.mark(giveWord);
+
+import foo, * as bar from "someModule";
+export const myWord = _Symbol("abc");
+export function giveWord() {
+  return _regeneratorRuntime.wrap(function giveWord$(_context) {
+    while (1) switch (_context.prev = _context.next) {
+      case 0:
+        _context.next = 2;
+        return myWord;
+
+      case 2:
+      case "end":
+        return _context.stop();
+    }
+  }, _marked, this);
+}
+foo;
+bar;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/input.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/input.mjs
new file mode 100644
index 0000000000..368b106310
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/input.mjs
@@ -0,0 +1,5 @@
+import foo from "foo";
+
+class Example {
+  method() {}
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/options.json
new file mode 100644
index 0000000000..5d178b7e91
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/options.json
@@ -0,0 +1,7 @@
+{
+  "plugins": [
+    ["transform-runtime", { "corejs": 2 }],
+    "transform-modules-commonjs",
+    "transform-classes"
+  ]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/output.js
new file mode 100644
index 0000000000..8b91c079a6
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules-helpers/output.js
@@ -0,0 +1,23 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime-corejs2/helpers/interopRequireDefault");
+
+var _classCallCheck2 = _interopRequireDefault(require("@babel/runtime-corejs2/helpers/classCallCheck"));
+
+var _createClass2 = _interopRequireDefault(require("@babel/runtime-corejs2/helpers/createClass"));
+
+var _foo = _interopRequireDefault(require("foo"));
+
+let Example =
+/*#__PURE__*/
+function () {
+  function Example() {
+    (0, _classCallCheck2.default)(this, Example);
+  }
+
+  (0, _createClass2.default)(Example, [{
+    key: "method",
+    value: function method() {}
+  }]);
+  return Example;
+}();
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/input.mjs b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/input.mjs
new file mode 100644
index 0000000000..ce4c7df806
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/input.mjs
@@ -0,0 +1,4 @@
+import foo from "bar";
+foo;
+
+export * from "mod";
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/options.json
new file mode 100644
index 0000000000..f3b812fb39
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-modules-commonjs"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/output.js
new file mode 100644
index 0000000000..d7ece9528b
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/modules/output.js
@@ -0,0 +1,28 @@
+"use strict";
+
+var _interopRequireDefault = require("@babel/runtime-corejs2/helpers/interopRequireDefault");
+
+var _Object$defineProperty = require("@babel/runtime-corejs2/core-js/object/define-property");
+
+var _Object$keys = require("@babel/runtime-corejs2/core-js/object/keys");
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+
+var _bar = _interopRequireDefault(require("bar"));
+
+var _mod = require("mod");
+
+_Object$keys(_mod).forEach(function (key) {
+  if (key === "default" || key === "__esModule") return;
+
+  _Object$defineProperty(exports, key, {
+    enumerable: true,
+    get: function () {
+      return _mod[key];
+    }
+  });
+});
+
+_bar.default;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/input.js
new file mode 100644
index 0000000000..4e6a6de653
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/input.js
@@ -0,0 +1 @@
+class Foo {}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/options.json
new file mode 100644
index 0000000000..d30944afcb
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "helpers": false, "corejs": 2 }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/output.js
new file mode 100644
index 0000000000..b8dfb31983
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/no-helpers/output.js
@@ -0,0 +1,7 @@
+function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
+
+let Foo = function Foo() {
+  "use strict";
+
+  _classCallCheck(this, Foo);
+};
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/input.js
new file mode 100644
index 0000000000..ae6cc4d8c8
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/input.js
@@ -0,0 +1,2 @@
+void function* () {
+};
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/options.json
new file mode 100644
index 0000000000..5c04c77630
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/output.js
new file mode 100644
index 0000000000..a068476f99
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/regenerator-runtime/output.js
@@ -0,0 +1,13 @@
+var _regeneratorRuntime = require("@babel/runtime-corejs2/regenerator");
+
+void
+/*#__PURE__*/
+_regeneratorRuntime.mark(function _callee() {
+  return _regeneratorRuntime.wrap(function _callee$(_context) {
+    while (1) switch (_context.prev = _context.next) {
+      case 0:
+      case "end":
+        return _context.stop();
+    }
+  }, _callee, this);
+});
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/input.js
new file mode 100644
index 0000000000..49e71aa52d
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/input.js
@@ -0,0 +1 @@
+Symbol.iterator in Object(arr);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/options.json
new file mode 100644
index 0000000000..e0ebc58869
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["transform-runtime", { "corejs": 2 }],
+    "transform-regenerator"
+  ]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/output.js
new file mode 100644
index 0000000000..8d5e3c048d
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator-in/output.js
@@ -0,0 +1,3 @@
+var _isIterable = require("@babel/runtime-corejs2/core-js/is-iterable");
+
+_isIterable(Object(arr));
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/input.js
new file mode 100644
index 0000000000..ae1f0b9df5
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/input.js
@@ -0,0 +1 @@
+Symbol.iterator;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/options.json
new file mode 100644
index 0000000000..5c04c77630
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-regenerator"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/output.js
new file mode 100644
index 0000000000..dc708b45cc
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime-corejs2/symbol-iterator/output.js
@@ -0,0 +1,3 @@
+var _Symbol$iterator = require("@babel/runtime-corejs2/core-js/symbol/iterator");
+
+_Symbol$iterator;
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
index b5e3ecf4ad..60d3e2fb72 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/class/output.js
@@ -1,4 +1,4 @@
-var _classCallCheck = require("@babel/runtime/helpers/builtin/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
 
 let Foo = function Foo() {
   "use strict";
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
index ba3228c9cf..260de19e94 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/runtime/modules/output.js
@@ -1,6 +1,6 @@
 "use strict";
 
-var _interopRequireDefault = require("@babel/runtime/helpers/builtin/interopRequireDefault");
+var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
 
 Object.defineProperty(exports, "__esModule", {
   value: true
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/input.js
similarity index 100%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/input.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/input.js
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/options.json
new file mode 100644
index 0000000000..95636c5bb4
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2, "useESModules": true }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/output.js
new file mode 100644
index 0000000000..fd691a2742
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs-useES6Modules/output.js
@@ -0,0 +1,23 @@
+var _classCallCheck = require("@babel/runtime-corejs2/helpers/esm/classCallCheck");
+
+var _possibleConstructorReturn = require("@babel/runtime-corejs2/helpers/esm/possibleConstructorReturn");
+
+var _getPrototypeOf = require("@babel/runtime-corejs2/helpers/esm/getPrototypeOf");
+
+var _inherits = require("@babel/runtime-corejs2/helpers/esm/inherits");
+
+let Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  _inherits(Foo, _Bar);
+
+  function Foo() {
+    _classCallCheck(this, Foo);
+
+    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
+  }
+
+  return Foo;
+}(Bar);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/input.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/input.js
similarity index 100%
rename from packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/input.js
rename to packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/input.js
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/options.json
new file mode 100644
index 0000000000..2972db7d1a
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/options.json
@@ -0,0 +1,3 @@
+{
+  "plugins": [["transform-runtime", { "corejs": 2 }], "transform-classes"]
+}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/output.js
new file mode 100644
index 0000000000..91eb87aa16
--- /dev/null
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejs/output.js
@@ -0,0 +1,23 @@
+var _classCallCheck = require("@babel/runtime-corejs2/helpers/classCallCheck");
+
+var _possibleConstructorReturn = require("@babel/runtime-corejs2/helpers/possibleConstructorReturn");
+
+var _getPrototypeOf = require("@babel/runtime-corejs2/helpers/getPrototypeOf");
+
+var _inherits = require("@babel/runtime-corejs2/helpers/inherits");
+
+let Foo =
+/*#__PURE__*/
+function (_Bar) {
+  "use strict";
+
+  _inherits(Foo, _Bar);
+
+  function Foo() {
+    _classCallCheck(this, Foo);
+
+    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
+  }
+
+  return Foo;
+}(Bar);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
deleted file mode 100644
index 1057edde11..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": [["transform-runtime", { "corejsVersion": 2, "useESModules": true }], "transform-classes"]
-}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
deleted file mode 100644
index 9d1599d1f2..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion-useES6Modules/output.js
+++ /dev/null
@@ -1,23 +0,0 @@
-var _classCallCheck = require("@babel/runtime/helpers/es6/classCallCheck");
-
-var _possibleConstructorReturn = require("@babel/runtime/helpers/es6/possibleConstructorReturn");
-
-var _getPrototypeOf = require("@babel/runtime/helpers/es6/getPrototypeOf");
-
-var _inherits = require("@babel/runtime/helpers/es6/inherits");
-
-let Foo =
-/*#__PURE__*/
-function (_Bar) {
-  "use strict";
-
-  _inherits(Foo, _Bar);
-
-  function Foo() {
-    _classCallCheck(this, Foo);
-
-    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
-  }
-
-  return Foo;
-}(Bar);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
deleted file mode 100644
index b5668b025a..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "plugins": [["transform-runtime", { "corejsVersion": 2 }], "transform-classes"]
-}
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
deleted file mode 100644
index 39882dcd46..0000000000
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/corejsVersion/output.js
+++ /dev/null
@@ -1,23 +0,0 @@
-var _classCallCheck = require("@babel/runtime/helpers/classCallCheck");
-
-var _possibleConstructorReturn = require("@babel/runtime/helpers/possibleConstructorReturn");
-
-var _getPrototypeOf = require("@babel/runtime/helpers/getPrototypeOf");
-
-var _inherits = require("@babel/runtime/helpers/inherits");
-
-let Foo =
-/*#__PURE__*/
-function (_Bar) {
-  "use strict";
-
-  _inherits(Foo, _Bar);
-
-  function Foo() {
-    _classCallCheck(this, Foo);
-
-    return _possibleConstructorReturn(this, _getPrototypeOf(Foo).apply(this, arguments));
-  }
-
-  return Foo;
-}(Bar);
diff --git a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
index 889a5a8d73..d2863837c4 100644
--- a/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
+++ b/packages/babel-plugin-transform-runtime/test/fixtures/use-options/useESModules/output.js
@@ -1,10 +1,10 @@
-var _classCallCheck = require("@babel/runtime/helpers/es6/builtin/classCallCheck");
+var _classCallCheck = require("@babel/runtime/helpers/esm/classCallCheck");
 
-var _possibleConstructorReturn = require("@babel/runtime/helpers/es6/builtin/possibleConstructorReturn");
+var _possibleConstructorReturn = require("@babel/runtime/helpers/esm/possibleConstructorReturn");
 
-var _getPrototypeOf = require("@babel/runtime/helpers/es6/builtin/getPrototypeOf");
+var _getPrototypeOf = require("@babel/runtime/helpers/esm/getPrototypeOf");
 
-var _inherits = require("@babel/runtime/helpers/es6/builtin/inherits");
+var _inherits = require("@babel/runtime/helpers/esm/inherits");
 
 let Foo =
 /*#__PURE__*/
diff --git a/packages/babel-runtime-corejs2/.npmignore b/packages/babel-runtime-corejs2/.npmignore
new file mode 100644
index 0000000000..f980694583
--- /dev/null
+++ b/packages/babel-runtime-corejs2/.npmignore
@@ -0,0 +1,3 @@
+src
+test
+*.log
diff --git a/packages/babel-runtime-corejs2/README.md b/packages/babel-runtime-corejs2/README.md
new file mode 100644
index 0000000000..bcae9d9c14
--- /dev/null
+++ b/packages/babel-runtime-corejs2/README.md
@@ -0,0 +1,19 @@
+# @babel/runtime-corejs2
+
+> babel's modular runtime helpers with core-js@2 polyfilling
+
+See our website [@babel/runtime-corejs2](https://babeljs.io/docs/en/next/babel-runtime-corejs2.html) for more information.
+
+## Install
+
+Using npm:
+
+```sh
+npm install --save-dev @babel/runtime-corejs2
+```
+
+or using yarn:
+
+```sh
+yarn add @babel/runtime-corejs2 --dev
+```
diff --git a/packages/babel-runtime/core-js/map.js b/packages/babel-runtime-corejs2/core-js/map.js
similarity index 100%
rename from packages/babel-runtime/core-js/map.js
rename to packages/babel-runtime-corejs2/core-js/map.js
diff --git a/packages/babel-runtime/helpers/es6/iterableToArray.js b/packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js
similarity index 100%
rename from packages/babel-runtime/helpers/es6/iterableToArray.js
rename to packages/babel-runtime-corejs2/helpers/esm/iterableToArray.js
diff --git a/packages/babel-runtime/helpers/builtin/es6/temporalRef.js b/packages/babel-runtime-corejs2/helpers/esm/temporalRef.js
similarity index 100%
rename from packages/babel-runtime/helpers/builtin/es6/temporalRef.js
rename to packages/babel-runtime-corejs2/helpers/esm/temporalRef.js
diff --git a/packages/babel-runtime/helpers/builtin/es6/toArray.js b/packages/babel-runtime-corejs2/helpers/esm/toArray.js
similarity index 100%
rename from packages/babel-runtime/helpers/builtin/es6/toArray.js
rename to packages/babel-runtime-corejs2/helpers/esm/toArray.js
diff --git a/packages/babel-runtime-corejs2/helpers/iterableToArray.js b/packages/babel-runtime-corejs2/helpers/iterableToArray.js
new file mode 100644
index 0000000000..c7834a3122
--- /dev/null
+++ b/packages/babel-runtime-corejs2/helpers/iterableToArray.js
@@ -0,0 +1,9 @@
+var _Array$from = require("../core-js/array/from");
+
+var _isIterable = require("../core-js/is-iterable");
+
+function _iterableToArray(iter) {
+  if (_isIterable(Object(iter)) || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
+}
+
+module.exports = _iterableToArray;
\ No newline at end of file
diff --git a/packages/babel-runtime/helpers/builtin/temporalRef.js b/packages/babel-runtime-corejs2/helpers/temporalRef.js
similarity index 100%
rename from packages/babel-runtime/helpers/builtin/temporalRef.js
rename to packages/babel-runtime-corejs2/helpers/temporalRef.js
diff --git a/packages/babel-runtime/helpers/builtin/toArray.js b/packages/babel-runtime-corejs2/helpers/toArray.js
similarity index 100%
rename from packages/babel-runtime/helpers/builtin/toArray.js
rename to packages/babel-runtime-corejs2/helpers/toArray.js
diff --git a/packages/babel-runtime-corejs2/package.json b/packages/babel-runtime-corejs2/package.json
new file mode 100644
index 0000000000..3f0edf5900
--- /dev/null
+++ b/packages/babel-runtime-corejs2/package.json
@@ -0,0 +1,12 @@
+{
+  "name": "@babel/runtime-corejs2",
+  "version": "7.0.0-beta.51",
+  "description": "babel's modular runtime helpers with core-js@2 polyfilling",
+  "license": "MIT",
+  "repository": "https://github.com/babel/babel/tree/master/packages/babel-runtime-corejs2",
+  "author": "Sebastian McKenzie <sebmck@gmail.com>",
+  "dependencies": {
+    "core-js": "^2.5.7",
+    "regenerator-runtime": "^0.12.0"
+  }
+}
diff --git a/packages/babel-runtime-corejs2/regenerator/index.js b/packages/babel-runtime-corejs2/regenerator/index.js
new file mode 100644
index 0000000000..9fd4158a6d
--- /dev/null
+++ b/packages/babel-runtime-corejs2/regenerator/index.js
@@ -0,0 +1 @@
+module.exports = require("regenerator-runtime");
diff --git a/packages/babel-runtime/README.md b/packages/babel-runtime/README.md
index ec85bb0b52..75087e3560 100644
--- a/packages/babel-runtime/README.md
+++ b/packages/babel-runtime/README.md
@@ -1,6 +1,6 @@
 # @babel/runtime
 
-> babel selfContained runtime
+> babel's modular runtime helpers
 
 See our website [@babel/runtime](https://babeljs.io/docs/en/next/babel-runtime.html) for more information.
 
diff --git a/packages/babel-runtime/core-js.js b/packages/babel-runtime/core-js.js
deleted file mode 100644
index 709f7e3252..0000000000
--- a/packages/babel-runtime/core-js.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = require("core-js/library");
diff --git a/packages/babel-runtime/helpers/builtin/iterableToArray.js b/packages/babel-runtime/helpers/builtin/iterableToArray.js
deleted file mode 100644
index e917e57937..0000000000
--- a/packages/babel-runtime/helpers/builtin/iterableToArray.js
+++ /dev/null
@@ -1,5 +0,0 @@
-function _iterableToArray(iter) {
-  if (Symbol.iterator in Object(iter) || Object.prototype.toString.call(iter) === "[object Arguments]") return Array.from(iter);
-}
-
-module.exports = _iterableToArray;
\ No newline at end of file
diff --git a/packages/babel-runtime/helpers/builtin/es6/iterableToArray.js b/packages/babel-runtime/helpers/esm/iterableToArray.js
similarity index 100%
rename from packages/babel-runtime/helpers/builtin/es6/iterableToArray.js
rename to packages/babel-runtime/helpers/esm/iterableToArray.js
diff --git a/packages/babel-runtime/helpers/es6/temporalRef.js b/packages/babel-runtime/helpers/esm/temporalRef.js
similarity index 100%
rename from packages/babel-runtime/helpers/es6/temporalRef.js
rename to packages/babel-runtime/helpers/esm/temporalRef.js
diff --git a/packages/babel-runtime/helpers/es6/toArray.js b/packages/babel-runtime/helpers/esm/toArray.js
similarity index 100%
rename from packages/babel-runtime/helpers/es6/toArray.js
rename to packages/babel-runtime/helpers/esm/toArray.js
diff --git a/packages/babel-runtime/helpers/iterableToArray.js b/packages/babel-runtime/helpers/iterableToArray.js
index c7834a3122..e917e57937 100644
--- a/packages/babel-runtime/helpers/iterableToArray.js
+++ b/packages/babel-runtime/helpers/iterableToArray.js
@@ -1,9 +1,5 @@
-var _Array$from = require("../core-js/array/from");
-
-var _isIterable = require("../core-js/is-iterable");
-
 function _iterableToArray(iter) {
-  if (_isIterable(Object(iter)) || Object.prototype.toString.call(iter) === "[object Arguments]") return _Array$from(iter);
+  if (Symbol.iterator in Object(iter) || Object.prototype.toString.call(iter) === "[object Arguments]") return Array.from(iter);
 }
 
 module.exports = _iterableToArray;
\ No newline at end of file
diff --git a/packages/babel-runtime/package.json b/packages/babel-runtime/package.json
index 79fc3de77f..4edabdb87f 100644
--- a/packages/babel-runtime/package.json
+++ b/packages/babel-runtime/package.json
@@ -1,12 +1,11 @@
 {
   "name": "@babel/runtime",
   "version": "7.0.0-beta.55",
-  "description": "babel selfContained runtime",
+  "description": "babel's modular runtime helpers",
   "license": "MIT",
   "repository": "https://github.com/babel/babel/tree/master/packages/babel-runtime",
   "author": "Sebastian McKenzie <sebmck@gmail.com>",
   "dependencies": {
-    "core-js": "^2.5.7",
     "regenerator-runtime": "^0.12.0"
   }
 }