diff --git a/packages/babel-core/src/config/option-manager.js b/packages/babel-core/src/config/option-manager.js
index 641440c353..0c4cd84ffa 100644
--- a/packages/babel-core/src/config/option-manager.js
+++ b/packages/babel-core/src/config/option-manager.js
@@ -163,17 +163,19 @@ class OptionManager {
       filenameRelative: opts.filename,
     });
 
-    const basenameRelative = path.basename(opts.filenameRelative);
+    if (typeof opts.filenameRelative === "string") {
+      const basenameRelative = path.basename(opts.filenameRelative);
 
-    if (path.extname(opts.filenameRelative) === ".mjs") {
-      opts.sourceType = "module";
+      if (path.extname(opts.filenameRelative) === ".mjs") {
+        opts.sourceType = "module";
+      }
+
+      defaults(opts, {
+        sourceFileName: basenameRelative,
+        sourceMapTarget: basenameRelative,
+      });
     }
 
-    defaults(opts, {
-      sourceFileName: basenameRelative,
-      sourceMapTarget: basenameRelative,
-    });
-
     return {
       options: opts,
       passes: this.passes,
@@ -461,7 +463,6 @@ function createInitialOptions() {
   return {
     sourceType: "module",
     babelrc: true,
-    filename: "unknown",
     code: true,
     ast: true,
     comments: true,
diff --git a/packages/babel-core/src/transformation/file/generate.js b/packages/babel-core/src/transformation/file/generate.js
index 39327d75dc..85b072e59b 100644
--- a/packages/babel-core/src/transformation/file/generate.js
+++ b/packages/babel-core/src/transformation/file/generate.js
@@ -24,7 +24,7 @@ export default function generateCode(
     Object.assign(
       {
         // General generator flags.
-        filename: opts.filename,
+        filename: opts.filename || "unknown",
         auxiliaryCommentBefore: opts.auxiliaryCommentBefore,
         auxiliaryCommentAfter: opts.auxiliaryCommentAfter,
         retainLines: opts.retainLines,
@@ -35,9 +35,9 @@ export default function generateCode(
 
         // Source-map generation flags.
         sourceMaps: opts.sourceMaps,
-        sourceMapTarget: opts.sourceMapTarget,
+        sourceMapTarget: opts.sourceMapTarget || "unknown",
         sourceRoot: opts.sourceRoot,
-        sourceFileName: opts.sourceFileName,
+        sourceFileName: opts.sourceFileName || "unknown",
       },
       opts.generatorOpts,
     ),
diff --git a/packages/babel-core/src/transformation/normalize-file.js b/packages/babel-core/src/transformation/normalize-file.js
index 72975a7951..c0722bb62e 100644
--- a/packages/babel-core/src/transformation/normalize-file.js
+++ b/packages/babel-core/src/transformation/normalize-file.js
@@ -70,7 +70,7 @@ function parser(options, code) {
     if (loc) {
       err.loc = null;
       err.message =
-        `${options.filename}: ${err.message}\n` +
+        `${options.filename || "unknown"}: ${err.message}\n` +
         codeFrameColumns(
           code,
           {
diff --git a/packages/babel-core/src/transformation/normalize-opts.js b/packages/babel-core/src/transformation/normalize-opts.js
index f9844de43e..591b6c4fbd 100644
--- a/packages/babel-core/src/transformation/normalize-opts.js
+++ b/packages/babel-core/src/transformation/normalize-opts.js
@@ -7,7 +7,7 @@ export default function normalizeOptions(config: ResolvedConfig): {} {
     parserOpts: Object.assign(
       {
         sourceType: config.options.sourceType,
-        sourceFileName: config.options.filename,
+        sourceFileName: config.options.filename || "unknown",
         plugins: [],
       },
       config.options.parserOpts,
diff --git a/packages/babel-core/src/transformation/plugin-pass.js b/packages/babel-core/src/transformation/plugin-pass.js
index 000f7e4c62..c526d4256b 100644
--- a/packages/babel-core/src/transformation/plugin-pass.js
+++ b/packages/babel-core/src/transformation/plugin-pass.js
@@ -7,11 +7,14 @@ export default class PluginPass {
   key: ?string;
   file: File;
   opts: Object;
+  filename: string | void;
 
   constructor(file: File, key: ?string, options: ?Object) {
     this.key = key;
     this.file = file;
     this.opts = options || {};
+    this.filename =
+      typeof file.opts.filename === "string" ? file.opts.filename : undefined;
   }
 
   set(key: mixed, val: mixed) {
diff --git a/packages/babel-plugin-transform-modules-umd/src/index.js b/packages/babel-plugin-transform-modules-umd/src/index.js
index de21197ffc..c806e8c3c6 100644
--- a/packages/babel-plugin-transform-modules-umd/src/index.js
+++ b/packages/babel-plugin-transform-modules-umd/src/index.js
@@ -44,10 +44,15 @@ export default function({ types: t }, options) {
   /**
    * Build the assignment statements that initialize the UMD global.
    */
-  function buildBrowserInit(browserGlobals, exactGlobals, file, moduleName) {
+  function buildBrowserInit(
+    browserGlobals,
+    exactGlobals,
+    filename,
+    moduleName,
+  ) {
     const moduleNameOrBasename = moduleName
       ? moduleName.value
-      : basename(file.opts.filename, extname(file.opts.filename));
+      : basename(filename, extname(filename));
     let globalToAssign = t.memberExpression(
       t.identifier("global"),
       t.identifier(t.toIdentifier(moduleNameOrBasename)),
@@ -204,7 +209,7 @@ export default function({ types: t }, options) {
               GLOBAL_TO_ASSIGN: buildBrowserInit(
                 browserGlobals,
                 exactGlobals,
-                this.file,
+                this.filename || "unknown",
                 moduleName,
               ),
             }),
diff --git a/packages/babel-plugin-transform-react-display-name/src/index.js b/packages/babel-plugin-transform-react-display-name/src/index.js
index 6b5a0b5f90..3ed305380f 100644
--- a/packages/babel-plugin-transform-react-display-name/src/index.js
+++ b/packages/babel-plugin-transform-react-display-name/src/index.js
@@ -52,14 +52,13 @@ export default function({ types: t }) {
     visitor: {
       ExportDefaultDeclaration({ node }, state) {
         if (isCreateClass(node.declaration)) {
-          let displayName = path.basename(
-            state.file.opts.filename,
-            path.extname(state.file.opts.filename),
-          );
+          const filename = state.filename || "unknown";
+
+          let displayName = path.basename(filename, path.extname(filename));
 
           // ./{module name}/index.js
           if (displayName === "index") {
-            displayName = path.basename(path.dirname(state.file.opts.filename));
+            displayName = path.basename(path.dirname(filename));
           }
 
           addDisplayName(displayName, node.declaration);
diff --git a/packages/babel-plugin-transform-react-jsx-source/src/index.js b/packages/babel-plugin-transform-react-jsx-source/src/index.js
index 76a5cea1ee..d76aed50f8 100644
--- a/packages/babel-plugin-transform-react-jsx-source/src/index.js
+++ b/packages/babel-plugin-transform-react-jsx-source/src/index.js
@@ -50,7 +50,7 @@ export default function({ types: t }) {
       }
 
       if (!state.fileNameIdentifier) {
-        const fileName = state.file.opts.filename || "";
+        const fileName = state.filename || "";
 
         const fileNameIdentifier = path.scope.generateUidIdentifier(
           FILE_NAME_VAR,