diff --git a/src/browser/ui/React.js b/src/browser/ui/React.js
index 6215fe3434..5232085661 100644
--- a/src/browser/ui/React.js
+++ b/src/browser/ui/React.js
@@ -39,10 +39,12 @@ ReactDefaultInjection.inject();
 
 var createElement = ReactElement.createElement;
 var createFactory = ReactElement.createFactory;
+var cloneElement = ReactElement.cloneElement;
 
 if (__DEV__) {
   createElement = ReactElementValidator.createElement;
   createFactory = ReactElementValidator.createFactory;
+  cloneElement = ReactElementValidator.cloneElement;
 }
 
 var render = ReactPerf.measure('React', 'render', ReactMount.render);
@@ -62,6 +64,7 @@ var React = {
   },
   createClass: ReactClass.createClass,
   createElement: createElement,
+  cloneElement: cloneElement,
   createFactory: createFactory,
   createMixin: function(mixin) {
     // Currently a noop. Will be used to validate and trace mixins.
diff --git a/src/classic/element/ReactElement.js b/src/classic/element/ReactElement.js
index c582f95a6a..13313ae418 100644
--- a/src/classic/element/ReactElement.js
+++ b/src/classic/element/ReactElement.js
@@ -228,6 +228,60 @@ ReactElement.cloneAndReplaceProps = function(oldElement, newProps) {
   return newElement;
 };
 
+ReactElement.cloneElement = function(element, config, children) {
+  var propName;
+
+  // Original props are copied
+  var props = assign({}, element.props);
+
+  // Reserved names are extracted
+  var key = element.key;
+  var ref = element.ref;
+
+  // Owner will be preserved, unless ref is overridden
+  var owner = element._owner;
+
+  if (config != null) {
+    if (config.ref !== undefined) {
+      // Silently steal the ref from the parent.
+      ref = config.ref;
+      owner = ReactCurrentOwner.current;
+    }
+    if (config.key !== undefined) {
+      key = '' + config.key;
+    }
+    // Remaining properties override existing props
+    for (propName in config) {
+      if (config.hasOwnProperty(propName) &&
+          !RESERVED_PROPS.hasOwnProperty(propName)) {
+        props[propName] = config[propName];
+      }
+    }
+  }
+
+  // Children can be more than one argument, and those are transferred onto
+  // the newly allocated props object.
+  var childrenLength = arguments.length - 2;
+  if (childrenLength === 1) {
+    props.children = children;
+  } else if (childrenLength > 1) {
+    var childArray = Array(childrenLength);
+    for (var i = 0; i < childrenLength; i++) {
+      childArray[i] = arguments[i + 2];
+    }
+    props.children = childArray;
+  }
+
+  return new ReactElement(
+    element.type,
+    key,
+    ref,
+    owner,
+    element._context,
+    props
+  );
+};
+
 /**
  * @param {?object} object
  * @return {boolean} True if `object` is a valid component.
diff --git a/src/classic/element/ReactElementValidator.js b/src/classic/element/ReactElementValidator.js
index 35cd38d6cf..1f25c23d42 100644
--- a/src/classic/element/ReactElementValidator.js
+++ b/src/classic/element/ReactElementValidator.js
@@ -336,6 +336,42 @@ function checkAndWarnForMutatedProps(element) {
   }
 }
 
+/**
+ * Given an element, validate that its props follow the propTypes definition,
+ * provided by the type.
+ *
+ * @param {ReactElement} element
+ */
+function validatePropTypes(element) {
+  if (element.type == null) {
+    // This has already warned. Don't throw.
+    return;
+  }
+  // Extract the component class from the element. Converts string types
+  // to a composite class which may have propTypes.
+  // TODO: Validating a string's propTypes is not decoupled from the
+  // rendering target which is problematic.
+  var componentClass = ReactNativeComponent.getComponentClassForElement(
+    element
+  );
+  var name = componentClass.displayName || componentClass.name;
+  if (componentClass.propTypes) {
+    checkPropTypes(
+      name,
+      componentClass.propTypes,
+      element.props,
+      ReactPropTypeLocations.prop
+    );
+  }
+  if (typeof componentClass.getDefaultProps === 'function') {
+    warning(
+      componentClass.getDefaultProps.isReactClassApproved,
+      'getDefaultProps is only used on classic React.createClass ' +
+      'definitions. Use a static property named `defaultProps` instead.'
+    );
+  }
+}
+
 var ReactElementValidator = {
 
   checkAndWarnForMutatedProps: checkAndWarnForMutatedProps,
@@ -362,33 +398,7 @@ var ReactElementValidator = {
       validateChildKeys(arguments[i], type);
     }
 
-    if (type) {
-      // Extract the component class from the element. Converts string types
-      // to a composite class which may have propTypes.
-      // TODO: Validating a string's propTypes is not decoupled from the
-      // rendering target which is problematic.
-      var componentClass = ReactNativeComponent.getComponentClassForElement(
-        element
-      );
-      var name = componentClass.displayName || componentClass.name;
-      if (__DEV__) {
-        if (componentClass.propTypes) {
-          checkPropTypes(
-            name,
-            componentClass.propTypes,
-            element.props,
-            ReactPropTypeLocations.prop
-          );
-        }
-      }
-      if (typeof componentClass.getDefaultProps === 'function') {
-        warning(
-          componentClass.getDefaultProps.isReactClassApproved,
-          'getDefaultProps is only used on classic React.createClass ' +
-          'definitions. Use a static property named `defaultProps` instead.'
-        );
-      }
-    }
+    validatePropTypes(element);
 
     return element;
   },
@@ -428,6 +438,15 @@ var ReactElementValidator = {
 
 
     return validatedFactory;
+  },
+
+  cloneElement: function(element, props, children) {
+    var newElement = ReactElement.cloneElement.apply(this, arguments);
+    for (var i = 2; i < arguments.length; i++) {
+      validateChildKeys(arguments[i], newElement.type);
+    }
+    validatePropTypes(newElement);
+    return newElement;
   }
 
 };
diff --git a/src/classic/element/__tests__/ReactElementClone-test.js b/src/classic/element/__tests__/ReactElementClone-test.js
new file mode 100644
index 0000000000..66b086c341
--- /dev/null
+++ b/src/classic/element/__tests__/ReactElementClone-test.js
@@ -0,0 +1,268 @@
+/**
+ * Copyright 2013-2015, 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.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+require('mock-modules');
+
+var mocks = require('mocks');
+
+var React;
+var ReactTestUtils;
+
+describe('ReactElementClone', function() {
+
+  beforeEach(function() {
+    React = require('React');
+    ReactTestUtils = require('ReactTestUtils');
+  });
+
+  it('should clone a DOM component with new props', function() {
+    var Grandparent = React.createClass({
+      render: function() {
+        return <Parent child={<div className="child" />} />;
+      }
+    });
+    var Parent = React.createClass({
+      render: function() {
+        return (
+          <div className="parent">
+            {React.cloneElement(this.props.child, { className: 'xyz' })}
+          </div>
+        );
+      }
+    });
+    var component = ReactTestUtils.renderIntoDocument(<Grandparent />);
+    expect(component.getDOMNode().childNodes[0].className).toBe('xyz');
+  });
+
+  it('should clone a composite component with new props', function() {
+    var Child = React.createClass({
+      render: function() {
+        return <div className={this.props.className} />;
+      }
+    });
+    var Grandparent = React.createClass({
+      render: function() {
+        return <Parent child={<Child className="child" />} />;
+      }
+    });
+    var Parent = React.createClass({
+      render: function() {
+        return (
+          <div className="parent">
+            {React.cloneElement(this.props.child, { className: 'xyz' })}
+          </div>
+        );
+      }
+    });
+    var component = ReactTestUtils.renderIntoDocument(<Grandparent />);
+    expect(component.getDOMNode().childNodes[0].className).toBe('xyz');
+  });
+
+  it('should keep the original ref if it is not overridden', function() {
+    var Grandparent = React.createClass({
+      render: function() {
+        return <Parent child={<div ref="yolo" />} />;
+      }
+    });
+
+    var Parent = React.createClass({
+      render: function() {
+        return (
+          <div>
+            {React.cloneElement(this.props.child, { className: 'xyz' })}
+          </div>
+        );
+      }
+    });
+
+    var component = ReactTestUtils.renderIntoDocument(<Grandparent />);
+    expect(component.refs.yolo.tagName).toBe('DIV');
+  });
+
+  it('should transfer the key property', function() {
+    var Component = React.createClass({
+      render: function() {
+        return null;
+      }
+    });
+    var clone = React.cloneElement(<Component />, {key: 'xyz'});
+    expect(clone.key).toBe('xyz');
+  });
+
+  it('should transfer children', function() {
+    var Component = React.createClass({
+      render: function() {
+        expect(this.props.children).toBe('xyz');
+        return <div />;
+      }
+    });
+
+    ReactTestUtils.renderIntoDocument(
+      React.cloneElement(<Component />, {children: 'xyz'})
+    );
+  });
+
+  it('should shallow clone children', function() {
+    var Component = React.createClass({
+      render: function() {
+        expect(this.props.children).toBe('xyz');
+        return <div />;
+      }
+    });
+
+    ReactTestUtils.renderIntoDocument(
+      React.cloneElement(<Component>xyz</Component>, {})
+    );
+  });
+
+  it('should accept children as rest arguments', function() {
+    var Component = React.createClass({
+      render: function() {
+        return null;
+      }
+    });
+
+    var clone = React.cloneElement(
+      <Component>xyz</Component>,
+      { children: <Component /> },
+      <div />,
+      <span />
+    );
+
+    expect(clone.props.children).toEqual([
+      <div />,
+      <span />
+    ]);
+  });
+
+  it('should support keys and refs', function() {
+    var Parent = React.createClass({
+      render: function() {
+        var clone =
+          React.cloneElement(this.props.children, {key: 'xyz', ref: 'xyz'});
+        expect(clone.key).toBe('xyz');
+        expect(clone.ref).toBe('xyz');
+        return <div>{clone}</div>;
+      }
+    });
+
+    var Grandparent = React.createClass({
+      render: function() {
+        return <Parent ref="parent"><span key="abc" /></Parent>;
+      }
+    });
+
+    var component = ReactTestUtils.renderIntoDocument(<Grandparent />);
+    expect(component.refs.parent.refs.xyz.tagName).toBe('SPAN');
+  });
+
+  it('should steal the ref if a new ref is specified', function() {
+    var Parent = React.createClass({
+      render: function() {
+        var clone = React.cloneElement(this.props.children, {ref: 'xyz'});
+        return <div>{clone}</div>;
+      }
+    });
+
+    var Grandparent = React.createClass({
+      render: function() {
+        return <Parent ref="parent"><span ref="child" /></Parent>;
+      }
+    });
+
+    var component = ReactTestUtils.renderIntoDocument(<Grandparent />);
+    expect(component.refs.child).toBeUndefined();
+    expect(component.refs.parent.refs.xyz.tagName).toBe('SPAN');
+  });
+
+  it('should overwrite props', function() {
+    var Component = React.createClass({
+      render: function() {
+        expect(this.props.myprop).toBe('xyz');
+        return <div />;
+      }
+    });
+
+    ReactTestUtils.renderIntoDocument(
+      React.cloneElement(<Component myprop="abc" />, {myprop: 'xyz'})
+    );
+  });
+
+  it('warns for keys for arrays of elements in rest args', function() {
+    spyOn(console, 'warn');
+
+    React.cloneElement(<div />, null, [<div />, <div />]);
+
+    expect(console.warn.argsForCall.length).toBe(1);
+    expect(console.warn.argsForCall[0][0]).toContain(
+      'Each child in an array or iterator should have a unique "key" prop.'
+    );
+  });
+
+  it('does not warns for arrays of elements with keys', function() {
+    spyOn(console, 'warn');
+
+    React.cloneElement(<div />, null, [<div key="#1" />, <div key="#2" />]);
+
+    expect(console.warn.argsForCall.length).toBe(0);
+  });
+
+  it('does not warn when the element is directly in rest args', function() {
+    spyOn(console, 'warn');
+
+    React.cloneElement(<div />, null, <div />, <div />);
+
+    expect(console.warn.argsForCall.length).toBe(0);
+  });
+
+  it('does not warn when the array contains a non-element', function() {
+    spyOn(console, 'warn');
+
+    React.cloneElement(<div />, null, [{}, {}]);
+
+    expect(console.warn.argsForCall.length).toBe(0);
+  });
+
+  it('should check declared prop types after clone', function() {
+    spyOn(console, 'warn');
+    var Component = React.createClass({
+      propTypes: {
+        color: React.PropTypes.string.isRequired
+      },
+      render: function() {
+        return React.createElement('div', null, 'My color is ' + this.color);
+      }
+    });
+    var Parent = React.createClass({
+      render: function() {
+        return React.cloneElement(this.props.child, {color: 123});
+      }
+    });
+    var GrandParent = React.createClass({
+      render: function() {
+        return React.createElement(
+          Parent,
+          { child: React.createElement(Component, {color: 'red'}) }
+        );
+      }
+    });
+    ReactTestUtils.renderIntoDocument(React.createElement(GrandParent));
+    expect(console.warn.argsForCall.length).toBe(1);
+    expect(console.warn.calls[0].args[0]).toBe(
+      'Warning: Failed propType: ' +
+      'Invalid prop `color` of type `number` supplied to `Component`, ' +
+      'expected `string`. Check the render method of `Parent`.'
+    );
+  });
+
+});