diff --git a/.babelrc b/.babelrc
index 8eb255a729f00..73803b050c24c 100644
--- a/.babelrc
+++ b/.babelrc
@@ -20,6 +20,7 @@
     "transform-es2015-block-scoping",
     "transform-es2015-modules-commonjs",
     "transform-es3-member-expression-literals",
-    "transform-es3-property-literals"
+    "transform-es3-property-literals",
+    "./scripts/babel/transform-object-assign-require"
   ]
 }
diff --git a/gulpfile.js b/gulpfile.js
index 21bd6c5d11c1b..f885ea349a670 100644
--- a/gulpfile.js
+++ b/gulpfile.js
@@ -35,7 +35,7 @@ var babelOpts = {
         {},
         require('fbjs/module-map'),
         {
-          'Object.assign': 'object-assign',
+          'object-assign': 'object-assign',
         }
       ),
     }],
diff --git a/scripts/babel/transform-object-assign-require.js b/scripts/babel/transform-object-assign-require.js
new file mode 100644
index 0000000000000..dc1dfebd2dd86
--- /dev/null
+++ b/scripts/babel/transform-object-assign-require.js
@@ -0,0 +1,40 @@
+/**
+ * Copyright 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+module.exports = function autoImporter(babel) {
+  const t = babel.types;
+
+  return {
+    pre: function() {
+      // map from module to generated identifier
+      this.id = null;
+    },
+
+    visitor: {
+      CallExpression: function (path, file) {
+        if (path.get("callee").matchesPattern("Object.assign")) {
+          // generate identifier and require if it hasn't been already
+          if (!this.id) {
+            this.id = path.scope.generateUidIdentifier('assign');
+            path.scope.getProgramParent().push({
+              id: this.id,
+              init: t.callExpression(
+                t.identifier('require'),
+                [t.stringLiteral('object-assign')]
+              ),
+            });
+          }
+          path.node.callee = this.id;
+        }
+      },
+    },
+  };
+};
diff --git a/scripts/jest/preprocessor.js b/scripts/jest/preprocessor.js
index ab2141e8eaed2..29f0d03b06979 100644
--- a/scripts/jest/preprocessor.js
+++ b/scripts/jest/preprocessor.js
@@ -32,7 +32,7 @@ var babelOptions = {
         {},
         moduleMap,
         {
-          'Object.assign': 'object-assign',
+          'object-assign': 'object-assign',
         }
       ),
     }],
diff --git a/src/addons/transitions/ReactCSSTransitionGroup.js b/src/addons/transitions/ReactCSSTransitionGroup.js
index 532018847aaf1..4177ec790b2e8 100644
--- a/src/addons/transitions/ReactCSSTransitionGroup.js
+++ b/src/addons/transitions/ReactCSSTransitionGroup.js
@@ -13,8 +13,6 @@
 
 var React = require('React');
 
-var assign = require('Object.assign');
-
 var ReactTransitionGroup = require('ReactTransitionGroup');
 var ReactCSSTransitionGroupChild = require('ReactCSSTransitionGroupChild');
 
@@ -87,7 +85,7 @@ var ReactCSSTransitionGroup = React.createClass({
   render: function() {
     return React.createElement(
       ReactTransitionGroup,
-      assign({}, this.props, {childFactory: this._wrapChild})
+      Object.assign({}, this.props, {childFactory: this._wrapChild})
     );
   },
 });
diff --git a/src/addons/transitions/ReactTransitionGroup.js b/src/addons/transitions/ReactTransitionGroup.js
index 816edfacc57a5..6d6df1a80b608 100644
--- a/src/addons/transitions/ReactTransitionGroup.js
+++ b/src/addons/transitions/ReactTransitionGroup.js
@@ -14,7 +14,6 @@
 var React = require('React');
 var ReactTransitionChildMapping = require('ReactTransitionChildMapping');
 
-var assign = require('Object.assign');
 var emptyFunction = require('emptyFunction');
 
 var ReactTransitionGroup = React.createClass({
@@ -193,7 +192,7 @@ var ReactTransitionGroup = React.createClass({
       this.performEnter(key);
     } else {
       this.setState(function(state) {
-        var newChildren = assign({}, state.children);
+        var newChildren = Object.assign({}, state.children);
         delete newChildren[key];
         return {children: newChildren};
       });
diff --git a/src/addons/update.js b/src/addons/update.js
index 7c8ba4e3b1dbb..cc2434e2bd309 100644
--- a/src/addons/update.js
+++ b/src/addons/update.js
@@ -13,7 +13,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var keyOf = require('keyOf');
 var invariant = require('invariant');
 var hasOwnProperty = {}.hasOwnProperty;
@@ -22,7 +21,7 @@ function shallowCopy(x) {
   if (Array.isArray(x)) {
     return x.concat();
   } else if (x && typeof x === 'object') {
-    return assign(new x.constructor(), x);
+    return Object.assign(new x.constructor(), x);
   } else {
     return x;
   }
@@ -102,7 +101,7 @@ function update(value, spec) {
       COMMAND_MERGE,
       nextValue
     );
-    assign(nextValue, spec[COMMAND_MERGE]);
+    Object.assign(nextValue, spec[COMMAND_MERGE]);
   }
 
   if (hasOwnProperty.call(spec, COMMAND_PUSH)) {
diff --git a/src/isomorphic/React.js b/src/isomorphic/React.js
index 5037feb7a4a67..37109d6ea13f0 100644
--- a/src/isomorphic/React.js
+++ b/src/isomorphic/React.js
@@ -20,7 +20,6 @@ var ReactElementValidator = require('ReactElementValidator');
 var ReactPropTypes = require('ReactPropTypes');
 var ReactVersion = require('ReactVersion');
 
-var assign = require('Object.assign');
 var onlyChild = require('onlyChild');
 
 var createElement = ReactElement.createElement;
@@ -68,7 +67,7 @@ var React = {
   version: ReactVersion,
 
   // Hook for JSX spread, don't use this for anything else.
-  __spread: assign,
+  __spread: Object.assign,
 };
 
 module.exports = React;
diff --git a/src/isomorphic/classic/class/ReactClass.js b/src/isomorphic/classic/class/ReactClass.js
index 8a2a6f30dd515..56f479a42e991 100644
--- a/src/isomorphic/classic/class/ReactClass.js
+++ b/src/isomorphic/classic/class/ReactClass.js
@@ -17,7 +17,6 @@ var ReactPropTypeLocations = require('ReactPropTypeLocations');
 var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 var ReactNoopUpdateQueue = require('ReactNoopUpdateQueue');
 
-var assign = require('Object.assign');
 var emptyObject = require('emptyObject');
 var invariant = require('invariant');
 var keyMirror = require('keyMirror');
@@ -331,7 +330,7 @@ var RESERVED_SPEC_KEYS = {
         ReactPropTypeLocations.childContext
       );
     }
-    Constructor.childContextTypes = assign(
+    Constructor.childContextTypes = Object.assign(
       {},
       Constructor.childContextTypes,
       childContextTypes
@@ -345,7 +344,7 @@ var RESERVED_SPEC_KEYS = {
         ReactPropTypeLocations.context
       );
     }
-    Constructor.contextTypes = assign(
+    Constructor.contextTypes = Object.assign(
       {},
       Constructor.contextTypes,
       contextTypes
@@ -373,7 +372,7 @@ var RESERVED_SPEC_KEYS = {
         ReactPropTypeLocations.prop
       );
     }
-    Constructor.propTypes = assign(
+    Constructor.propTypes = Object.assign(
       {},
       Constructor.propTypes,
       propTypes
@@ -726,7 +725,7 @@ var ReactClassMixin = {
 };
 
 var ReactClassComponent = function() {};
-assign(
+Object.assign(
   ReactClassComponent.prototype,
   ReactComponent.prototype,
   ReactClassMixin
diff --git a/src/isomorphic/classic/element/ReactElement.js b/src/isomorphic/classic/element/ReactElement.js
index 6e371596d06d1..ee46a5f392dbb 100644
--- a/src/isomorphic/classic/element/ReactElement.js
+++ b/src/isomorphic/classic/element/ReactElement.js
@@ -13,7 +13,6 @@
 
 var ReactCurrentOwner = require('ReactCurrentOwner');
 
-var assign = require('Object.assign');
 var warning = require('warning');
 var canDefineProperty = require('canDefineProperty');
 
@@ -253,7 +252,7 @@ ReactElement.cloneElement = function(element, config, children) {
   var propName;
 
   // Original props are copied
-  var props = assign({}, element.props);
+  var props = Object.assign({}, element.props);
 
   // Reserved names are extracted
   var key = element.key;
diff --git a/src/isomorphic/deprecated/OrderedMap.js b/src/isomorphic/deprecated/OrderedMap.js
index 92cea05f828dd..4336cdc384495 100644
--- a/src/isomorphic/deprecated/OrderedMap.js
+++ b/src/isomorphic/deprecated/OrderedMap.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 
 var PREFIX = 'key:';
@@ -475,7 +474,7 @@ var OrderedMapMethods = {
   },
 };
 
-assign(OrderedMapImpl.prototype, OrderedMapMethods);
+Object.assign(OrderedMapImpl.prototype, OrderedMapMethods);
 
 var OrderedMap = {
   from: function(orderedMap) {
diff --git a/src/isomorphic/deprecated/ReactPropTransferer.js b/src/isomorphic/deprecated/ReactPropTransferer.js
index b3e2a8269d32c..da009cafe0acd 100644
--- a/src/isomorphic/deprecated/ReactPropTransferer.js
+++ b/src/isomorphic/deprecated/ReactPropTransferer.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var emptyFunction = require('emptyFunction');
 var joinClasses = require('joinClasses');
 
@@ -36,7 +35,7 @@ var transferStrategyMerge = createTransferStrategy(function(a, b) {
   // `merge` overrides the first object's (`props[key]` above) keys using the
   // second object's (`value`) keys. An object's style's existing `propA` would
   // get overridden. Flip the order here.
-  return assign({}, b, a);
+  return Object.assign({}, b, a);
 });
 
 /**
@@ -100,7 +99,7 @@ var ReactPropTransferer = {
    * @return {object} a new object containing both sets of props merged.
    */
   mergeProps: function(oldProps, newProps) {
-    return transferInto(assign({}, oldProps), newProps);
+    return transferInto(Object.assign({}, oldProps), newProps);
   },
 
 };
diff --git a/src/renderers/dom/client/ReactBrowserEventEmitter.js b/src/renderers/dom/client/ReactBrowserEventEmitter.js
index 5f5dc8d267e54..dd7334f48463b 100644
--- a/src/renderers/dom/client/ReactBrowserEventEmitter.js
+++ b/src/renderers/dom/client/ReactBrowserEventEmitter.js
@@ -16,7 +16,6 @@ var EventPluginRegistry = require('EventPluginRegistry');
 var ReactEventEmitterMixin = require('ReactEventEmitterMixin');
 var ViewportMetrics = require('ViewportMetrics');
 
-var assign = require('Object.assign');
 var getVendorPrefixedEventName = require('getVendorPrefixedEventName');
 var isEventSupported = require('isEventSupported');
 
@@ -175,7 +174,7 @@ function getListeningForDocument(mountAt) {
  *
  * @internal
  */
-var ReactBrowserEventEmitter = assign({}, ReactEventEmitterMixin, {
+var ReactBrowserEventEmitter = Object.assign({}, ReactEventEmitterMixin, {
 
   /**
    * Injectable event backend
diff --git a/src/renderers/dom/client/ReactEventListener.js b/src/renderers/dom/client/ReactEventListener.js
index 1d69e02086df4..bbdbbcf29115e 100644
--- a/src/renderers/dom/client/ReactEventListener.js
+++ b/src/renderers/dom/client/ReactEventListener.js
@@ -17,7 +17,6 @@ var PooledClass = require('PooledClass');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactUpdates = require('ReactUpdates');
 
-var assign = require('Object.assign');
 var getEventTarget = require('getEventTarget');
 var getUnboundedScrollPosition = require('getUnboundedScrollPosition');
 
@@ -44,7 +43,7 @@ function TopLevelCallbackBookKeeping(topLevelType, nativeEvent) {
   this.nativeEvent = nativeEvent;
   this.ancestors = [];
 }
-assign(TopLevelCallbackBookKeeping.prototype, {
+Object.assign(TopLevelCallbackBookKeeping.prototype, {
   destructor: function() {
     this.topLevelType = null;
     this.nativeEvent = null;
diff --git a/src/renderers/dom/client/ReactReconcileTransaction.js b/src/renderers/dom/client/ReactReconcileTransaction.js
index 1835a2dbbc74f..fedd883bf1cb9 100644
--- a/src/renderers/dom/client/ReactReconcileTransaction.js
+++ b/src/renderers/dom/client/ReactReconcileTransaction.js
@@ -17,7 +17,6 @@ var ReactBrowserEventEmitter = require('ReactBrowserEventEmitter');
 var ReactInputSelection = require('ReactInputSelection');
 var Transaction = require('Transaction');
 
-var assign = require('Object.assign');
 
 /**
  * Ensures that, when possible, the selection range (currently selected text
@@ -160,7 +159,7 @@ var Mixin = {
 };
 
 
-assign(ReactReconcileTransaction.prototype, Transaction.Mixin, Mixin);
+Object.assign(ReactReconcileTransaction.prototype, Transaction.Mixin, Mixin);
 
 PooledClass.addPoolingTo(ReactReconcileTransaction);
 
diff --git a/src/renderers/dom/client/eventPlugins/FallbackCompositionState.js b/src/renderers/dom/client/eventPlugins/FallbackCompositionState.js
index 68c12841e02a7..e26e259a0f125 100644
--- a/src/renderers/dom/client/eventPlugins/FallbackCompositionState.js
+++ b/src/renderers/dom/client/eventPlugins/FallbackCompositionState.js
@@ -13,7 +13,6 @@
 
 var PooledClass = require('PooledClass');
 
-var assign = require('Object.assign');
 var getTextContentAccessor = require('getTextContentAccessor');
 
 /**
@@ -33,7 +32,7 @@ function FallbackCompositionState(root) {
   this._fallbackText = null;
 }
 
-assign(FallbackCompositionState.prototype, {
+Object.assign(FallbackCompositionState.prototype, {
   destructor: function() {
     this._root = null;
     this._startText = null;
diff --git a/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js b/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js
index daad64d18e2cb..d3cdf3c399d3c 100644
--- a/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js
+++ b/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js
@@ -13,7 +13,6 @@
 
 var PooledClass = require('PooledClass');
 
-var assign = require('Object.assign');
 var emptyFunction = require('emptyFunction');
 var warning = require('warning');
 
@@ -111,7 +110,7 @@ function SyntheticEvent(dispatchConfig, targetInst, nativeEvent, nativeEventTarg
   return this;
 }
 
-assign(SyntheticEvent.prototype, {
+Object.assign(SyntheticEvent.prototype, {
 
   preventDefault: function() {
     this.defaultPrevented = true;
@@ -229,11 +228,11 @@ SyntheticEvent.augmentClass = function(Class, Interface) {
   E.prototype = Super.prototype;
   var prototype = new E();
 
-  assign(prototype, Class.prototype);
+  Object.assign(prototype, Class.prototype);
   Class.prototype = prototype;
   Class.prototype.constructor = Class;
 
-  Class.Interface = assign({}, Super.Interface, Interface);
+  Class.Interface = Object.assign({}, Super.Interface, Interface);
   Class.augmentClass = Super.augmentClass;
 
   PooledClass.addPoolingTo(Class, PooledClass.fourArgumentPooler);
diff --git a/src/renderers/dom/client/validateDOMNesting.js b/src/renderers/dom/client/validateDOMNesting.js
index d479ea9af9a44..431d80fd2d5db 100644
--- a/src/renderers/dom/client/validateDOMNesting.js
+++ b/src/renderers/dom/client/validateDOMNesting.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var emptyFunction = require('emptyFunction');
 var warning = require('warning');
 
@@ -76,7 +75,7 @@ if (__DEV__) {
   };
 
   var updatedAncestorInfo = function(oldInfo, tag, instance) {
-    var ancestorInfo = assign({}, oldInfo || emptyAncestorInfo);
+    var ancestorInfo = Object.assign({}, oldInfo || emptyAncestorInfo);
     var info = {tag: tag, instance: instance};
 
     if (inScopeTags.indexOf(tag) !== -1) {
diff --git a/src/renderers/dom/client/wrappers/ReactDOMInput.js b/src/renderers/dom/client/wrappers/ReactDOMInput.js
index e52c199b24a15..e9cd9b541ad91 100644
--- a/src/renderers/dom/client/wrappers/ReactDOMInput.js
+++ b/src/renderers/dom/client/wrappers/ReactDOMInput.js
@@ -16,7 +16,6 @@ var LinkedValueUtils = require('LinkedValueUtils');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactUpdates = require('ReactUpdates');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 var warning = require('warning');
 
@@ -69,7 +68,7 @@ var ReactDOMInput = {
     var value = LinkedValueUtils.getValue(props);
     var checked = LinkedValueUtils.getChecked(props);
 
-    var nativeProps = assign({
+    var nativeProps = Object.assign({
       // Make sure we set .type before any other properties (setting .value
       // before .type means .value is lost in IE11 and below)
       type: undefined,
diff --git a/src/renderers/dom/client/wrappers/ReactDOMOption.js b/src/renderers/dom/client/wrappers/ReactDOMOption.js
index 31e605003027e..917ed0ee4a167 100644
--- a/src/renderers/dom/client/wrappers/ReactDOMOption.js
+++ b/src/renderers/dom/client/wrappers/ReactDOMOption.js
@@ -14,7 +14,6 @@
 var ReactChildren = require('ReactChildren');
 var ReactDOMSelect = require('ReactDOMSelect');
 
-var assign = require('Object.assign');
 var warning = require('warning');
 
 /**
@@ -59,7 +58,7 @@ var ReactDOMOption = {
   },
 
   getNativeProps: function(inst, props) {
-    var nativeProps = assign({selected: undefined, children: undefined}, props);
+    var nativeProps = Object.assign({selected: undefined, children: undefined}, props);
 
     // Read state only from initial mount because <select> updates value
     // manually; we need the initial state only for server rendering
diff --git a/src/renderers/dom/client/wrappers/ReactDOMSelect.js b/src/renderers/dom/client/wrappers/ReactDOMSelect.js
index f0ac23fca1a3d..2247fb6775e10 100644
--- a/src/renderers/dom/client/wrappers/ReactDOMSelect.js
+++ b/src/renderers/dom/client/wrappers/ReactDOMSelect.js
@@ -15,7 +15,6 @@ var LinkedValueUtils = require('LinkedValueUtils');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactUpdates = require('ReactUpdates');
 
-var assign = require('Object.assign');
 var warning = require('warning');
 
 var didWarnValueLink = false;
@@ -159,7 +158,7 @@ function updateOptions(inst, multiple, propValue) {
  */
 var ReactDOMSelect = {
   getNativeProps: function(inst, props) {
-    return assign({}, props, {
+    return Object.assign({}, props, {
       onChange: inst._wrapperState.onChange,
       value: undefined,
     });
diff --git a/src/renderers/dom/client/wrappers/ReactDOMTextarea.js b/src/renderers/dom/client/wrappers/ReactDOMTextarea.js
index ed5ac820f30b2..bf5508b7d80ab 100644
--- a/src/renderers/dom/client/wrappers/ReactDOMTextarea.js
+++ b/src/renderers/dom/client/wrappers/ReactDOMTextarea.js
@@ -16,7 +16,6 @@ var LinkedValueUtils = require('LinkedValueUtils');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactUpdates = require('ReactUpdates');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 var warning = require('warning');
 
@@ -68,7 +67,7 @@ var ReactDOMTextarea = {
 
     // Always set children to the same thing. In IE9, the selection range will
     // get reset if `textContent` is mutated.
-    var nativeProps = assign({}, props, {
+    var nativeProps = Object.assign({}, props, {
       defaultValue: undefined,
       value: undefined,
       children: inst._wrapperState.initialValue,
diff --git a/src/renderers/dom/server/ReactServerRenderingTransaction.js b/src/renderers/dom/server/ReactServerRenderingTransaction.js
index 6e585ef85910b..176a550c599aa 100644
--- a/src/renderers/dom/server/ReactServerRenderingTransaction.js
+++ b/src/renderers/dom/server/ReactServerRenderingTransaction.js
@@ -14,7 +14,6 @@
 var PooledClass = require('PooledClass');
 var Transaction = require('Transaction');
 
-var assign = require('Object.assign');
 
 /**
  * Executed within the scope of the `Transaction` instance. Consider these as
@@ -64,7 +63,7 @@ var Mixin = {
 };
 
 
-assign(
+Object.assign(
   ReactServerRenderingTransaction.prototype,
   Transaction.Mixin,
   Mixin
diff --git a/src/renderers/dom/shared/ReactDOMComponent.js b/src/renderers/dom/shared/ReactDOMComponent.js
index 3e789d33b14ac..808706d62b8dc 100644
--- a/src/renderers/dom/shared/ReactDOMComponent.js
+++ b/src/renderers/dom/shared/ReactDOMComponent.js
@@ -35,7 +35,6 @@ var ReactDOMTextarea = require('ReactDOMTextarea');
 var ReactMultiChild = require('ReactMultiChild');
 var ReactPerf = require('ReactPerf');
 
-var assign = require('Object.assign');
 var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
 var invariant = require('invariant');
 var isEventSupported = require('isEventSupported');
@@ -381,7 +380,7 @@ var newlineEatingTags = {
 // For HTML, certain tags cannot have children. This has the same purpose as
 // `omittedCloseTags` except that `menuitem` should still have its closing tag.
 
-var voidElementTags = assign({
+var voidElementTags = Object.assign({
   'menuitem': true,
 }, omittedCloseTags);
 
@@ -641,7 +640,7 @@ ReactDOMComponent.Mixin = {
               // See `_updateDOMProperties`. style block
               this._previousStyle = propValue;
             }
-            propValue = this._previousStyleCopy = assign({}, props.style);
+            propValue = this._previousStyleCopy = Object.assign({}, props.style);
           }
           propValue = CSSPropertyOperations.createMarkupForStyles(propValue, this);
         }
@@ -887,7 +886,7 @@ ReactDOMComponent.Mixin = {
             );
             this._previousStyle = nextProp;
           }
-          nextProp = this._previousStyleCopy = assign({}, nextProp);
+          nextProp = this._previousStyleCopy = Object.assign({}, nextProp);
         } else {
           this._previousStyleCopy = null;
         }
@@ -1064,7 +1063,7 @@ ReactPerf.measureMethods(ReactDOMComponent.Mixin, 'ReactDOMComponent', {
   receiveComponent: 'receiveComponent',
 });
 
-assign(
+Object.assign(
   ReactDOMComponent.prototype,
   ReactDOMComponent.Mixin,
   ReactMultiChild.Mixin
diff --git a/src/renderers/dom/shared/ReactDOMEmptyComponent.js b/src/renderers/dom/shared/ReactDOMEmptyComponent.js
index c15ec123d6ed7..81f894091de56 100644
--- a/src/renderers/dom/shared/ReactDOMEmptyComponent.js
+++ b/src/renderers/dom/shared/ReactDOMEmptyComponent.js
@@ -14,7 +14,6 @@
 var DOMLazyTree = require('DOMLazyTree');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 
-var assign = require('Object.assign');
 
 var ReactDOMEmptyComponent = function(instantiate) {
   // ReactCompositeComponent uses this:
@@ -25,7 +24,7 @@ var ReactDOMEmptyComponent = function(instantiate) {
   this._nativeContainerInfo = null;
   this._domID = null;
 };
-assign(ReactDOMEmptyComponent.prototype, {
+Object.assign(ReactDOMEmptyComponent.prototype, {
   mountComponent: function(
     transaction,
     nativeParent,
diff --git a/src/renderers/dom/shared/ReactDOMTextComponent.js b/src/renderers/dom/shared/ReactDOMTextComponent.js
index cba23539eaf5f..9a69c7f97762a 100644
--- a/src/renderers/dom/shared/ReactDOMTextComponent.js
+++ b/src/renderers/dom/shared/ReactDOMTextComponent.js
@@ -16,7 +16,6 @@ var DOMLazyTree = require('DOMLazyTree');
 var ReactDOMComponentTree = require('ReactDOMComponentTree');
 var ReactPerf = require('ReactPerf');
 
-var assign = require('Object.assign');
 var escapeTextContentForBrowser = require('escapeTextContentForBrowser');
 var invariant = require('invariant');
 var validateDOMNesting = require('validateDOMNesting');
@@ -51,7 +50,7 @@ var ReactDOMTextComponent = function(text) {
   this._commentNodes = null;
 };
 
-assign(ReactDOMTextComponent.prototype, {
+Object.assign(ReactDOMTextComponent.prototype, {
 
   /**
    * Creates the markup for this text node. This node is not intended to have
diff --git a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
index 2fb18a526323b..d26c6156e00fb 100644
--- a/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
+++ b/src/renderers/dom/shared/__tests__/ReactDOMComponent-test.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 
 describe('ReactDOMComponent', function() {
   var React;
@@ -623,7 +622,7 @@ describe('ReactDOMComponent', function() {
         this._currentElement = {props: initialProps};
         this._rootNodeID = 'test';
       };
-      assign(NodeStub.prototype, ReactDOMComponent.Mixin);
+      Object.assign(NodeStub.prototype, ReactDOMComponent.Mixin);
 
       genMarkup = function(props) {
         var transaction = new ReactReconcileTransaction();
@@ -672,7 +671,7 @@ describe('ReactDOMComponent', function() {
         this._currentElement = {props: initialProps};
         this._rootNodeID = 'test';
       };
-      assign(NodeStub.prototype, ReactDOMComponent.Mixin);
+      Object.assign(NodeStub.prototype, ReactDOMComponent.Mixin);
 
       genMarkup = function(props) {
         var transaction = new ReactReconcileTransaction();
diff --git a/src/renderers/shared/event/__tests__/EventPluginRegistry-test.js b/src/renderers/shared/event/__tests__/EventPluginRegistry-test.js
index d781ba21b604b..7f06e58c13020 100644
--- a/src/renderers/shared/event/__tests__/EventPluginRegistry-test.js
+++ b/src/renderers/shared/event/__tests__/EventPluginRegistry-test.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 
 describe('EventPluginRegistry', function() {
   var EventPluginRegistry;
@@ -22,7 +21,7 @@ describe('EventPluginRegistry', function() {
     EventPluginRegistry._resetEventPlugins();
 
     createPlugin = function(properties) {
-      return assign({extractEvents: function() {}}, properties);
+      return Object.assign({extractEvents: function() {}}, properties);
     };
   });
 
diff --git a/src/renderers/shared/reconciler/ReactCompositeComponent.js b/src/renderers/shared/reconciler/ReactCompositeComponent.js
index 9e636294b55d8..0472e1fa86e88 100644
--- a/src/renderers/shared/reconciler/ReactCompositeComponent.js
+++ b/src/renderers/shared/reconciler/ReactCompositeComponent.js
@@ -24,7 +24,6 @@ var ReactPropTypeLocationNames = require('ReactPropTypeLocationNames');
 var ReactReconciler = require('ReactReconciler');
 var ReactUpdateQueue = require('ReactUpdateQueue');
 
-var assign = require('Object.assign');
 var emptyObject = require('emptyObject');
 var invariant = require('invariant');
 var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
@@ -526,7 +525,7 @@ var ReactCompositeComponentMixin = {
           name
         );
       }
-      return assign({}, currentContext, childContext);
+      return Object.assign({}, currentContext, childContext);
     }
     return currentContext;
   },
@@ -759,10 +758,10 @@ var ReactCompositeComponentMixin = {
       return queue[0];
     }
 
-    var nextState = assign({}, replace ? queue[0] : inst.state);
+    var nextState = Object.assign({}, replace ? queue[0] : inst.state);
     for (var i = replace ? 1 : 0; i < queue.length; i++) {
       var partial = queue[i];
-      assign(
+      Object.assign(
         nextState,
         typeof partial === 'function' ?
           partial.call(inst, nextState, props, context) :
diff --git a/src/renderers/shared/reconciler/ReactDefaultBatchingStrategy.js b/src/renderers/shared/reconciler/ReactDefaultBatchingStrategy.js
index 2023f59c2adb5..904dc1f803c18 100644
--- a/src/renderers/shared/reconciler/ReactDefaultBatchingStrategy.js
+++ b/src/renderers/shared/reconciler/ReactDefaultBatchingStrategy.js
@@ -14,7 +14,6 @@
 var ReactUpdates = require('ReactUpdates');
 var Transaction = require('Transaction');
 
-var assign = require('Object.assign');
 var emptyFunction = require('emptyFunction');
 
 var RESET_BATCHED_UPDATES = {
@@ -35,7 +34,7 @@ function ReactDefaultBatchingStrategyTransaction() {
   this.reinitializeTransaction();
 }
 
-assign(
+Object.assign(
   ReactDefaultBatchingStrategyTransaction.prototype,
   Transaction.Mixin,
   {
diff --git a/src/renderers/shared/reconciler/ReactNativeComponent.js b/src/renderers/shared/reconciler/ReactNativeComponent.js
index 42fe1108a594d..7f280349556f6 100644
--- a/src/renderers/shared/reconciler/ReactNativeComponent.js
+++ b/src/renderers/shared/reconciler/ReactNativeComponent.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 
 var autoGenerateWrapperClass = null;
@@ -34,7 +33,7 @@ var ReactNativeComponentInjection = {
   // This accepts a keyed object with classes as values. Each key represents a
   // tag. That particular tag will use this class instead of the generic one.
   injectComponentClasses: function(componentClasses) {
-    assign(tagToComponentClass, componentClasses);
+    Object.assign(tagToComponentClass, componentClasses);
   },
 };
 
diff --git a/src/renderers/shared/reconciler/ReactSimpleEmptyComponent.js b/src/renderers/shared/reconciler/ReactSimpleEmptyComponent.js
index e38fdcb7caeb1..0565a01644182 100644
--- a/src/renderers/shared/reconciler/ReactSimpleEmptyComponent.js
+++ b/src/renderers/shared/reconciler/ReactSimpleEmptyComponent.js
@@ -13,13 +13,12 @@
 
 var ReactReconciler = require('ReactReconciler');
 
-var assign = require('Object.assign');
 
 var ReactSimpleEmptyComponent = function(placeholderElement, instantiate) {
   this._currentElement = null;
   this._renderedComponent = instantiate(placeholderElement);
 };
-assign(ReactSimpleEmptyComponent.prototype, {
+Object.assign(ReactSimpleEmptyComponent.prototype, {
   mountComponent: function(
     transaction,
     nativeParent,
diff --git a/src/renderers/shared/reconciler/ReactUpdates.js b/src/renderers/shared/reconciler/ReactUpdates.js
index 3f67588743afa..6fd1d2f3b5284 100644
--- a/src/renderers/shared/reconciler/ReactUpdates.js
+++ b/src/renderers/shared/reconciler/ReactUpdates.js
@@ -18,7 +18,6 @@ var ReactPerf = require('ReactPerf');
 var ReactReconciler = require('ReactReconciler');
 var Transaction = require('Transaction');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 
 var dirtyComponents = [];
@@ -74,7 +73,7 @@ function ReactUpdatesFlushTransaction() {
   );
 }
 
-assign(
+Object.assign(
   ReactUpdatesFlushTransaction.prototype,
   Transaction.Mixin,
   {
diff --git a/src/renderers/shared/reconciler/instantiateReactComponent.js b/src/renderers/shared/reconciler/instantiateReactComponent.js
index cb0208f92a68f..796e037b9958b 100644
--- a/src/renderers/shared/reconciler/instantiateReactComponent.js
+++ b/src/renderers/shared/reconciler/instantiateReactComponent.js
@@ -15,7 +15,6 @@ var ReactCompositeComponent = require('ReactCompositeComponent');
 var ReactEmptyComponent = require('ReactEmptyComponent');
 var ReactNativeComponent = require('ReactNativeComponent');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 var warning = require('warning');
 
@@ -23,7 +22,7 @@ var warning = require('warning');
 var ReactCompositeComponentWrapper = function(element) {
   this.construct(element);
 };
-assign(
+Object.assign(
   ReactCompositeComponentWrapper.prototype,
   ReactCompositeComponent.Mixin,
   {
diff --git a/src/shared/utils/CallbackQueue.js b/src/shared/utils/CallbackQueue.js
index c594e30370f64..647c3887109cb 100644
--- a/src/shared/utils/CallbackQueue.js
+++ b/src/shared/utils/CallbackQueue.js
@@ -13,7 +13,6 @@
 
 var PooledClass = require('PooledClass');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 
 /**
@@ -32,7 +31,7 @@ function CallbackQueue() {
   this._contexts = null;
 }
 
-assign(CallbackQueue.prototype, {
+Object.assign(CallbackQueue.prototype, {
 
   /**
    * Enqueues a callback to be invoked when `notifyAll` is invoked.
diff --git a/src/shared/utils/__tests__/Transaction-test.js b/src/shared/utils/__tests__/Transaction-test.js
index 83857026b607a..ee474a1cc414f 100644
--- a/src/shared/utils/__tests__/Transaction-test.js
+++ b/src/shared/utils/__tests__/Transaction-test.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 
 var Transaction;
 
@@ -46,7 +45,7 @@ describe('Transaction', function() {
       this.secondCloseParam = INIT_ERRORED;  // WILL be set to something else
       this.lastCloseParam = INIT_ERRORED;    // WON'T be set to something else
     };
-    assign(TestTransaction.prototype, Transaction.Mixin);
+    Object.assign(TestTransaction.prototype, Transaction.Mixin);
     TestTransaction.prototype.getTransactionWrappers = function() {
       return [
         {
@@ -97,7 +96,7 @@ describe('Transaction', function() {
       this.secondCloseParam = INIT_ERRORED;  // WILL be set to something else
       this.lastCloseParam = INIT_ERRORED;    // WILL be set to something else
     };
-    assign(TestTransaction.prototype, Transaction.Mixin);
+    Object.assign(TestTransaction.prototype, Transaction.Mixin);
     TestTransaction.prototype.getTransactionWrappers = function() {
       return [
         {
@@ -158,7 +157,7 @@ describe('Transaction', function() {
       this.secondCloseParam = INIT_ERRORED;  // WILL be set to something else
       this.lastCloseParam = INIT_ERRORED;    // WILL be set to something else
     };
-    assign(TestTransaction.prototype, Transaction.Mixin);
+    Object.assign(TestTransaction.prototype, Transaction.Mixin);
     // Now, none of the close/inits throw, but the operation we wrap will throw.
     TestTransaction.prototype.getTransactionWrappers = function() {
       return [
@@ -222,7 +221,7 @@ describe('Transaction', function() {
     var TestTransaction = function() {
       this.reinitializeTransaction();
     };
-    assign(TestTransaction.prototype, Transaction.Mixin);
+    Object.assign(TestTransaction.prototype, Transaction.Mixin);
     var exceptionMsg = 'This exception should throw.';
     TestTransaction.prototype.getTransactionWrappers = function() {
       return [
@@ -251,7 +250,7 @@ describe('Transaction', function() {
       this.reinitializeTransaction();
       this.firstCloseParam = INIT_ERRORED; // WILL be set to something else
     };
-    assign(TestTransaction.prototype, Transaction.Mixin);
+    Object.assign(TestTransaction.prototype, Transaction.Mixin);
     TestTransaction.prototype.getTransactionWrappers = function() {
       return [
         {
@@ -279,7 +278,7 @@ describe('Transaction', function() {
     var NestedTransaction = function() {
       this.reinitializeTransaction();
     };
-    assign(NestedTransaction.prototype, Transaction.Mixin);
+    Object.assign(NestedTransaction.prototype, Transaction.Mixin);
     NestedTransaction.prototype.getTransactionWrappers = function() {
       return [
         {
diff --git a/src/shared/utils/deprecated.js b/src/shared/utils/deprecated.js
index c34e0f444fbdb..fd8edec6e4319 100644
--- a/src/shared/utils/deprecated.js
+++ b/src/shared/utils/deprecated.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 var warning = require('warning');
 
 /**
@@ -48,7 +47,7 @@ function deprecated(fnName, newModule, newPackage, ctx, fn) {
     };
     // We need to make sure all properties of the original fn are copied over.
     // In particular, this is needed to support PropTypes
-    return assign(newFn, fn);
+    return Object.assign(newFn, fn);
   }
 
   return fn;
diff --git a/src/test/ReactDefaultPerfAnalysis.js b/src/test/ReactDefaultPerfAnalysis.js
index a5d0d55b70b04..bf7cb30feca6b 100644
--- a/src/test/ReactDefaultPerfAnalysis.js
+++ b/src/test/ReactDefaultPerfAnalysis.js
@@ -11,7 +11,6 @@
 
 'use strict';
 
-var assign = require('Object.assign');
 
 // Don't try to save users less than 1.2ms (a number I made up)
 var DONT_CARE_THRESHOLD = 1.2;
@@ -65,7 +64,7 @@ function getExclusiveSummary(measurements) {
 
   for (var i = 0; i < measurements.length; i++) {
     var measurement = measurements[i];
-    var allIDs = assign(
+    var allIDs = Object.assign(
       {},
       measurement.exclusive,
       measurement.inclusive
@@ -117,7 +116,7 @@ function getInclusiveSummary(measurements, onlyClean) {
 
   for (var i = 0; i < measurements.length; i++) {
     var measurement = measurements[i];
-    var allIDs = assign(
+    var allIDs = Object.assign(
       {},
       measurement.exclusive,
       measurement.inclusive
@@ -185,7 +184,7 @@ function getUnchangedComponents(measurement) {
       }
     });
   });
-  var allIDs = assign({}, measurement.exclusive, measurement.inclusive);
+  var allIDs = Object.assign({}, measurement.exclusive, measurement.inclusive);
 
   for (var id in allIDs) {
     var isDirty = false;
diff --git a/src/test/ReactTestUtils.js b/src/test/ReactTestUtils.js
index 4f8e4ebb38c2b..f331bf6e22b95 100644
--- a/src/test/ReactTestUtils.js
+++ b/src/test/ReactTestUtils.js
@@ -25,7 +25,6 @@ var ReactInstanceMap = require('ReactInstanceMap');
 var ReactUpdates = require('ReactUpdates');
 var SyntheticEvent = require('SyntheticEvent');
 
-var assign = require('Object.assign');
 var emptyObject = require('emptyObject');
 var findDOMNode = require('findDOMNode');
 var invariant = require('invariant');
@@ -396,7 +395,7 @@ NoopInternalComponent.prototype = {
 var ShallowComponentWrapper = function(element) {
   this.construct(element);
 };
-assign(
+Object.assign(
   ShallowComponentWrapper.prototype,
   ReactCompositeComponent.Mixin, {
     _instantiateReactComponent: function(element) {
@@ -499,7 +498,7 @@ function makeSimulator(eventType) {
       fakeNativeEvent,
       node
     );
-    assign(event, eventData);
+    Object.assign(event, eventData);
 
     if (dispatchConfig.phasedRegistrationNames) {
       EventPropagators.accumulateTwoPhaseDispatches(event);
@@ -560,7 +559,7 @@ buildSimulators();
 function makeNativeSimulator(eventType) {
   return function(domComponentOrNode, nativeEventData) {
     var fakeNativeEvent = new Event(eventType);
-    assign(fakeNativeEvent, nativeEventData);
+    Object.assign(fakeNativeEvent, nativeEventData);
     if (ReactTestUtils.isDOMComponent(domComponentOrNode)) {
       ReactTestUtils.simulateNativeEventOnDOMComponent(
         eventType,
diff --git a/src/test/reactComponentExpect.js b/src/test/reactComponentExpect.js
index ad0966c21191a..0905387025ad5 100644
--- a/src/test/reactComponentExpect.js
+++ b/src/test/reactComponentExpect.js
@@ -15,7 +15,6 @@
 var ReactInstanceMap = require('ReactInstanceMap');
 var ReactTestUtils = require('ReactTestUtils');
 
-var assign = require('Object.assign');
 var invariant = require('invariant');
 
 function reactComponentExpect(instance) {
@@ -47,7 +46,7 @@ function reactComponentExpectInternal(internalInstance) {
   this._instance = internalInstance;
 }
 
-assign(reactComponentExpectInternal.prototype, {
+Object.assign(reactComponentExpectInternal.prototype, {
   // Getters -------------------------------------------------------------------
 
   /**
diff --git a/src/umd/ReactUMDEntry.js b/src/umd/ReactUMDEntry.js
index ee02afd38acb5..dda6487594732 100644
--- a/src/umd/ReactUMDEntry.js
+++ b/src/umd/ReactUMDEntry.js
@@ -15,10 +15,9 @@ var ReactDOM = require('ReactDOM');
 var ReactDOMServer = require('ReactDOMServer');
 var React = require('React');
 
-var assign = require('Object.assign');
 
 // `version` will be added here by ReactIsomorphic.
-var ReactUMDEntry = assign({
+var ReactUMDEntry = Object.assign({
   __SECRET_DOM_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactDOM,
   __SECRET_DOM_SERVER_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactDOMServer,
 }, React);
diff --git a/src/umd/ReactWithAddonsUMDEntry.js b/src/umd/ReactWithAddonsUMDEntry.js
index e1934f2a59397..cf59eb9c85eda 100644
--- a/src/umd/ReactWithAddonsUMDEntry.js
+++ b/src/umd/ReactWithAddonsUMDEntry.js
@@ -15,10 +15,9 @@ var ReactDOM = require('ReactDOM');
 var ReactDOMServer = require('ReactDOMServer');
 var ReactWithAddons = require('ReactWithAddons');
 
-var assign = require('Object.assign');
 
 // `version` will be added here by ReactIsomorphic.
-var ReactWithAddonsUMDEntry = assign({
+var ReactWithAddonsUMDEntry = Object.assign({
   __SECRET_DOM_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactDOM,
   __SECRET_DOM_SERVER_DO_NOT_USE_OR_YOU_WILL_BE_FIRED: ReactDOMServer,
 }, ReactWithAddons);