diff --git a/lib/6to5/transformation/transformers/es6/.tail-call.js b/lib/6to5/transformation/transformers/es6/.tail-call.js
deleted file mode 100644
index cd942211e1..0000000000
--- a/lib/6to5/transformation/transformers/es6/.tail-call.js
+++ /dev/null
@@ -1,116 +0,0 @@
-"use strict";
-
-var t = require("../../../types");
-
-function transformExpression(node, scope, state) {
-  if (!node) return;
-
-  return (function subTransform(node) {
-    switch (node.type) {
-      case "ConditionalExpression":
-        // any value of ternary operator can be final one
-        subTransform(node.consequent);
-        subTransform(node.alternate);
-        break;
-
-      case "LogicalExpression":
-        // only right expression can be final and so optimized
-        subTransform(node.right);
-        break;
-
-      case "SequenceExpression":
-        // only last element of sequence can be optimized
-        var seq = node.expressions;
-        subTransform(seq[seq.length - 1]);
-        break;
-
-      case "CallExpression":
-        var callee = node.callee, thisBinding;
-        var args = [callee];
-
-        // bind `this` to object in member expressions
-        if (t.isMemberExpression(callee)) {
-          var object = state.wrapSideEffect(callee.object);
-          callee.object = object.expr;
-          thisBinding = object.ref;
-        }
-
-        if (node.arguments.length > 0 || thisBinding) {
-          args.push(t.arrayExpression(node.arguments));
-        }
-
-        if (thisBinding) {
-          args.push(thisBinding);
-        }
-
-        node.callee = state.getHelperRef();
-        node.arguments = args;
-        break;
-    }
-  })(node);
-}
-
-var functionChildrenVisitor = {
-  enter: function (node, parent, scope, state) {
-    if (t.isReturnStatement(node)) {
-      // prevent entrance by current visitor
-      this.skip();
-      // transform return argument into statement if
-      // it contains tail recursion
-      transformExpression(node.argument, scope, state);
-    } else if (t.isFunction(node)) {
-      // inner function's bodies are irrelevant
-      this.skip();
-    } else if (t.isTryStatement(parent)) {
-      if (node === parent.block) {
-        // `try`-blocks can't be optimized
-        this.skip();
-      } else if (parent.finalizer && node !== parent.finalizer) {
-        // `catch` clause followed by `finally` can't be optimized
-        this.skip();
-      }
-    }
-  }
-};
-
-var functionVisitor = {
-  enter: function (node, parent, scope, state) {
-    // traverse all child nodes of this function and find `arguments` and `this`
-    scope.traverse(node, functionChildrenVisitor, state);
-
-    return this.skip();
-  }
-};
-
-exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, scope, file) {
-  var tempId, helperRef;
-
-  var state = {
-    ownerId: node.id,
-
-    getHelperRef: function () {
-      return helperRef = helperRef || file.addHelper("tail-call");
-    },
-
-    wrapSideEffect: function (node) {
-      if (t.isIdentifier(node) || t.isLiteral(node)) {
-        return {expr: node, ref: node};
-      }
-      tempId = tempId || scope.generateUidIdentifier("temp");
-      return {
-        expr: t.assignmentExpression("=", tempId, node),
-        ref: tempId
-      };
-    }
-  };
-
-  // traverse the function and look for tail recursion
-  scope.traverse(node, functionVisitor, state);
-
-  if (tempId) {
-    t.ensureBlock(node).body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(tempId)
-    ]));
-  }
-};
diff --git a/test/fixtures/transformation/.es6-tail-call/call-apply/actual.js b/test/fixtures/transformation/.es6-tail-call/call-apply/actual.js
deleted file mode 100644
index 2bb42c6c81..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/call-apply/actual.js
+++ /dev/null
@@ -1,7 +0,0 @@
-(function f(n) {
-  if (n <= 0) {
-    console.log(this, arguments);
-    return "foo";
-  }
-  return Math.random() > 0.5 ? f.call(this, n - 1) : f.apply(this, [n - 1]);
-})(1e6) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/call-apply/expected.js b/test/fixtures/transformation/.es6-tail-call/call-apply/expected.js
deleted file mode 100644
index 5e763b2f23..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/call-apply/expected.js
+++ /dev/null
@@ -1,9 +0,0 @@
-"use strict";
-
-(function f(n) {
-  if (n <= 0) {
-    console.log(this, arguments);
-    return "foo";
-  }
-  return Math.random() > 0.5 ? to5Runtime.tailCall(f.call, [this, n - 1], f) : to5Runtime.tailCall(f.apply, [this, [n - 1]], f);
-})(1000000) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/cross-function/actual.js b/test/fixtures/transformation/.es6-tail-call/cross-function/actual.js
deleted file mode 100644
index 173a50bb62..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/cross-function/actual.js
+++ /dev/null
@@ -1,7 +0,0 @@
-function f(n) {
-  return n <= 0 ? "foo" : g(n - 1);
-}
-
-function g(n) {
-  return n <= 0 ? "goo" : f(n - 1);
-}
diff --git a/test/fixtures/transformation/.es6-tail-call/cross-function/expected.js b/test/fixtures/transformation/.es6-tail-call/cross-function/expected.js
deleted file mode 100644
index 9f3c8cbd66..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/cross-function/expected.js
+++ /dev/null
@@ -1,9 +0,0 @@
-"use strict";
-
-function f(n) {
-  return n <= 0 ? "foo" : to5Runtime.tailCall(g, [n - 1]);
-}
-
-function g(n) {
-  return n <= 0 ? "goo" : to5Runtime.tailCall(f, [n - 1]);
-}
diff --git a/test/fixtures/transformation/.es6-tail-call/expressions/actual.js b/test/fixtures/transformation/.es6-tail-call/expressions/actual.js
deleted file mode 100644
index 824fdf80d5..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/expressions/actual.js
+++ /dev/null
@@ -1,3 +0,0 @@
-(function f(n) {
-  return n <= 0 ? "foo" : (doSmth(), getTrueValue() && (getFalseValue() || f(n - 1)));
-})(1e6, true) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/expressions/expected.js b/test/fixtures/transformation/.es6-tail-call/expressions/expected.js
deleted file mode 100644
index 466a76628f..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/expressions/expected.js
+++ /dev/null
@@ -1,5 +0,0 @@
-"use strict";
-
-(function f(n) {
-  return n <= 0 ? "foo" : (doSmth(), getTrueValue() && (getFalseValue() || to5Runtime.tailCall(f, [n - 1])));
-})(1000000, true) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/options.json b/test/fixtures/transformation/.es6-tail-call/options.json
deleted file mode 100644
index 4c0c25eacc..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/options.json
+++ /dev/null
@@ -1,4 +0,0 @@
-{
-  "runtime": true,
-  "blacklist": []
-}
diff --git a/test/fixtures/transformation/.es6-tail-call/recursion/actual.js b/test/fixtures/transformation/.es6-tail-call/recursion/actual.js
deleted file mode 100644
index 67de2e6943..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/recursion/actual.js
+++ /dev/null
@@ -1,8 +0,0 @@
-(function f(n = getDefaultValue(), /* should be undefined after first pass */ m) {
-  if (n <= 0) {
-    return "foo";
-  }
-  // Should be clean (undefined) on each pass
-  var local;
-  return f(n - 1);
-})(1e6, true) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/recursion/expected.js b/test/fixtures/transformation/.es6-tail-call/recursion/expected.js
deleted file mode 100644
index 1920e61d56..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/recursion/expected.js
+++ /dev/null
@@ -1,11 +0,0 @@
-"use strict";
-
-(function f(_x, /* should be undefined after first pass */m) {
-  var n = arguments[0] === undefined ? getDefaultValue() : arguments[0];
-  if (n <= 0) {
-    return "foo";
-  }
-  // Should be clean (undefined) on each pass
-  var local;
-  return to5Runtime.tailCall(f, [n - 1]);
-})(1000000, true) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/side-effect/actual.js b/test/fixtures/transformation/.es6-tail-call/side-effect/actual.js
deleted file mode 100644
index 3bcab98c40..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/side-effect/actual.js
+++ /dev/null
@@ -1,7 +0,0 @@
-function f() {
-  return getObj().method();
-}
-
-function g() {
-  return getFalseValue() || getValue();
-}
diff --git a/test/fixtures/transformation/.es6-tail-call/side-effect/expected.js b/test/fixtures/transformation/.es6-tail-call/side-effect/expected.js
deleted file mode 100644
index f7598aa5b8..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/side-effect/expected.js
+++ /dev/null
@@ -1,10 +0,0 @@
-"use strict";
-
-function f() {
-  var _temp;
-  return to5Runtime.tailCall((_temp = getObj()).method, [], _temp);
-}
-
-function g() {
-  return getFalseValue() || to5Runtime.tailCall(getValue);
-}
diff --git a/test/fixtures/transformation/.es6-tail-call/try-catch/actual.js b/test/fixtures/transformation/.es6-tail-call/try-catch/actual.js
deleted file mode 100644
index 0a6be74326..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/try-catch/actual.js
+++ /dev/null
@@ -1,39 +0,0 @@
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    return f(n - 1);
-  } catch (e) {}
-})(1e6) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    throw new Error();
-  } catch (e) {
-    return f(n - 1);
-  }
-})(1e6) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    throw new Error();
-  } catch (e) {
-    return f(n - 1);
-  } finally {}
-})(1e6) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {} finally {
-    return f(n - 1);
-  }
-})(1e6) === "foo";
diff --git a/test/fixtures/transformation/.es6-tail-call/try-catch/expected.js b/test/fixtures/transformation/.es6-tail-call/try-catch/expected.js
deleted file mode 100644
index 1406f3adb3..0000000000
--- a/test/fixtures/transformation/.es6-tail-call/try-catch/expected.js
+++ /dev/null
@@ -1,41 +0,0 @@
-"use strict";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    return f(n - 1);
-  } catch (e) {}
-})(1000000) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    throw new Error();
-  } catch (e) {
-    return to5Runtime.tailCall(f, [n - 1]);
-  }
-})(1000000) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {
-    throw new Error();
-  } catch (e) {
-    return f(n - 1);
-  } finally {}
-})(1000000) === "foo";
-
-(function f(n) {
-  if (n <= 0) {
-    return "foo";
-  }
-  try {} finally {
-    return to5Runtime.tailCall(f, [n - 1]);
-  }
-})(1000000) === "foo";