diff --git a/modules/@angular/common/src/pipes/async_pipe.ts b/modules/@angular/common/src/pipes/async_pipe.ts
index bd0db25ccb..17123c0551 100644
--- a/modules/@angular/common/src/pipes/async_pipe.ts
+++ b/modules/@angular/common/src/pipes/async_pipe.ts
@@ -8,7 +8,8 @@
 
 import {ChangeDetectorRef, OnDestroy, Pipe, WrappedValue} from '@angular/core';
 import {EventEmitter, Observable} from '../facade/async';
-import {isBlank, isPresent, isPromise} from '../facade/lang';
+import {isBlank, isPresent} from '../facade/lang';
+import {isPromise} from '../private_import_core';
 import {InvalidPipeArgumentError} from './invalid_pipe_argument_error';
 
 interface SubscriptionStrategy {
diff --git a/modules/@angular/common/src/private_import_core.ts b/modules/@angular/common/src/private_import_core.ts
new file mode 100644
index 0000000000..0292fbf02f
--- /dev/null
+++ b/modules/@angular/common/src/private_import_core.ts
@@ -0,0 +1,11 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {__core_private__ as r} from '@angular/core';
+
+export const isPromise: typeof r.isPromise = r.isPromise;
diff --git a/modules/@angular/core/src/application_init.ts b/modules/@angular/core/src/application_init.ts
index e7c27af6ee..45657ce9db 100644
--- a/modules/@angular/core/src/application_init.ts
+++ b/modules/@angular/core/src/application_init.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {isPromise} from '../src/facade/lang';
+import {isPromise} from '../src/util/lang';
 
 import {Inject, Injectable, OpaqueToken, Optional} from './di';
 
diff --git a/modules/@angular/core/src/application_ref.ts b/modules/@angular/core/src/application_ref.ts
index 5fd20a7fb9..c1ac48631d 100644
--- a/modules/@angular/core/src/application_ref.ts
+++ b/modules/@angular/core/src/application_ref.ts
@@ -9,7 +9,8 @@
 import {ErrorHandler} from '../src/error_handler';
 import {ListWrapper} from '../src/facade/collection';
 import {unimplemented} from '../src/facade/errors';
-import {isBlank, isPresent, isPromise, stringify} from '../src/facade/lang';
+import {isBlank, isPresent, stringify} from '../src/facade/lang';
+import {isPromise} from '../src/util/lang';
 
 import {ApplicationInitStatus} from './application_init';
 import {APP_BOOTSTRAP_LISTENER, PLATFORM_INITIALIZER} from './application_tokens';
diff --git a/modules/@angular/core/src/core_private_export.ts b/modules/@angular/core/src/core_private_export.ts
index 778b848446..6a356841da 100644
--- a/modules/@angular/core/src/core_private_export.ts
+++ b/modules/@angular/core/src/core_private_export.ts
@@ -39,6 +39,7 @@ import * as reflector_reader from './reflection/reflector_reader';
 import * as reflection_types from './reflection/types';
 import * as api from './render/api';
 import * as decorators from './util/decorators';
+import {isPromise} from './util/lang';
 
 export var __core_private__: {
   isDefaultChangeDetectionStrategy: typeof constants.isDefaultChangeDetectionStrategy,
@@ -118,9 +119,11 @@ export var __core_private__: {
   ANY_STATE: typeof ANY_STATE_,
   DEFAULT_STATE: typeof DEFAULT_STATE_,
   EMPTY_STATE: typeof EMPTY_STATE_,
-  FILL_STYLE_FLAG: typeof FILL_STYLE_FLAG_, _ComponentStillLoadingError?: ComponentStillLoadingError
-  ComponentStillLoadingError: typeof ComponentStillLoadingError
-  } = {
+  FILL_STYLE_FLAG: typeof FILL_STYLE_FLAG_,
+  _ComponentStillLoadingError?: ComponentStillLoadingError,
+  ComponentStillLoadingError: typeof ComponentStillLoadingError,
+  isPromise: typeof isPromise
+} = {
   isDefaultChangeDetectionStrategy: constants.isDefaultChangeDetectionStrategy,
   ChangeDetectorStatus: constants.ChangeDetectorStatus,
   CHANGE_DETECTION_STRATEGY_VALUES: constants.CHANGE_DETECTION_STRATEGY_VALUES,
@@ -185,5 +188,6 @@ export var __core_private__: {
   DEFAULT_STATE: DEFAULT_STATE_,
   EMPTY_STATE: EMPTY_STATE_,
   FILL_STYLE_FLAG: FILL_STYLE_FLAG_,
-  ComponentStillLoadingError: ComponentStillLoadingError
+  ComponentStillLoadingError: ComponentStillLoadingError,
+  isPromise: isPromise
 };
diff --git a/modules/@angular/core/src/util/lang.ts b/modules/@angular/core/src/util/lang.ts
new file mode 100644
index 0000000000..314473971c
--- /dev/null
+++ b/modules/@angular/core/src/util/lang.ts
@@ -0,0 +1,13 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+export function isPromise(obj: any): obj is Promise<any> {
+  // allow any Promise/A+ compliant thenable.
+  // It's up to the caller to ensure that obj.then conforms to the spec
+  return !!obj && typeof obj.then === 'function';
+}
diff --git a/modules/@angular/core/test/util/lang_spec.ts b/modules/@angular/core/test/util/lang_spec.ts
new file mode 100644
index 0000000000..961a3fd6da
--- /dev/null
+++ b/modules/@angular/core/test/util/lang_spec.ts
@@ -0,0 +1,28 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {isPromise} from '@angular/core/src/util/lang';
+
+export function main() {
+  describe('isPromise', () => {
+    it('should be true for native Promises',
+       () => expect(isPromise(Promise.resolve(true))).toEqual(true));
+
+    it('should be true for thenables', () => expect(isPromise({then: () => {}})).toEqual(true));
+
+    it('should be false if "then" is not a function',
+       () => expect(isPromise({then: 0})).toEqual(false));
+
+    it('should be false if the argument has no "then" function',
+       () => expect(isPromise({})).toEqual(false));
+
+    it('should be false if the argument is undefined or null', () => {
+      expect(isPromise(undefined)).toEqual(false);
+      expect(isPromise(null)).toEqual(false);
+    });
+  });
+}
diff --git a/modules/@angular/core/testing/private_import_core.ts b/modules/@angular/core/testing/private_import_core.ts
new file mode 100644
index 0000000000..0292fbf02f
--- /dev/null
+++ b/modules/@angular/core/testing/private_import_core.ts
@@ -0,0 +1,11 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {__core_private__ as r} from '@angular/core';
+
+export const isPromise: typeof r.isPromise = r.isPromise;
diff --git a/modules/@angular/core/testing/testing_internal.ts b/modules/@angular/core/testing/testing_internal.ts
index 2dbcea90c9..27674f4da4 100644
--- a/modules/@angular/core/testing/testing_internal.ts
+++ b/modules/@angular/core/testing/testing_internal.ts
@@ -8,7 +8,8 @@
 
 import {AsyncTestCompleter} from './async_test_completer';
 import {StringMapWrapper} from './facade/collection';
-import {Math, global, isPromise} from './facade/lang';
+import {Math, global} from './facade/lang';
+import {isPromise} from './private_import_core';
 import {TestBed, getTestBed, inject} from './test_bed';
 
 export {AsyncTestCompleter} from './async_test_completer';
diff --git a/modules/@angular/facade/src/lang.ts b/modules/@angular/facade/src/lang.ts
index 3b6de25bbd..0d99a2a813 100644
--- a/modules/@angular/facade/src/lang.ts
+++ b/modules/@angular/facade/src/lang.ts
@@ -113,12 +113,6 @@ export function isStrictStringMap(obj: any): boolean {
   return isStringMap(obj) && Object.getPrototypeOf(obj) === STRING_MAP_PROTO;
 }
 
-export function isPromise(obj: any): boolean {
-  // allow any Promise/A+ compliant thenable.
-  // It's up to the caller to ensure that obj.then conforms to the spec
-  return isPresent(obj) && isFunction(obj.then);
-}
-
 export function isArray(obj: any): boolean {
   return Array.isArray(obj);
 }
diff --git a/modules/@angular/facade/test/lang_spec.ts b/modules/@angular/facade/test/lang_spec.ts
index e80e9400d1..823cc9ed0b 100644
--- a/modules/@angular/facade/test/lang_spec.ts
+++ b/modules/@angular/facade/test/lang_spec.ts
@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import {NumberWrapper, StringWrapper, escapeRegExp, hasConstructor, isPresent, isPromise, resolveEnumToken} from '../src/lang';
+import {NumberWrapper, StringWrapper, escapeRegExp, hasConstructor, isPresent, resolveEnumToken} from '../src/lang';
 
 enum UsefulEnum {
   MyToken,
@@ -153,22 +153,4 @@ export function main() {
          () => { expect(hasConstructor(new MySubclass(), MySuperclass)).toEqual(false); });
     });
   });
-  describe('isPromise', () => {
-    it('should be true for native Promises',
-       () => expect(isPromise(Promise.resolve(true))).toEqual(true));
-
-    it('should be true for thenables',
-       () => expect(isPromise({then: function() {}})).toEqual(true));
-
-    it('should be false if "then" is not a function',
-       () => expect(isPromise({then: 0})).toEqual(false));
-
-    it('should be false if the argument has no "then" function',
-       () => expect(isPromise({})).toEqual(false));
-
-    it('should be false if the argument is undefined or null', () => {
-      expect(isPromise(undefined)).toEqual(false);
-      expect(isPromise(null)).toEqual(false);
-    });
-  });
 }
diff --git a/modules/@angular/forms/src/model.ts b/modules/@angular/forms/src/model.ts
index c8b21b39d9..a79f98faec 100644
--- a/modules/@angular/forms/src/model.ts
+++ b/modules/@angular/forms/src/model.ts
@@ -12,7 +12,8 @@ import {composeAsyncValidators, composeValidators} from './directives/shared';
 import {AsyncValidatorFn, ValidatorFn} from './directives/validators';
 import {EventEmitter, Observable} from './facade/async';
 import {ListWrapper, StringMapWrapper} from './facade/collection';
-import {isBlank, isPresent, isPromise, isStringMap, normalizeBool} from './facade/lang';
+import {isBlank, isPresent, isStringMap, normalizeBool} from './facade/lang';
+import {isPromise} from './private_import_core';
 
 
 
diff --git a/modules/@angular/forms/src/private_import_core.ts b/modules/@angular/forms/src/private_import_core.ts
new file mode 100644
index 0000000000..0292fbf02f
--- /dev/null
+++ b/modules/@angular/forms/src/private_import_core.ts
@@ -0,0 +1,11 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {__core_private__ as r} from '@angular/core';
+
+export const isPromise: typeof r.isPromise = r.isPromise;
diff --git a/modules/@angular/forms/src/validators.ts b/modules/@angular/forms/src/validators.ts
index 29f7cfe039..196a9d4f7f 100644
--- a/modules/@angular/forms/src/validators.ts
+++ b/modules/@angular/forms/src/validators.ts
@@ -11,8 +11,10 @@ import {toPromise} from 'rxjs/operator/toPromise';
 
 import {AsyncValidatorFn, ValidatorFn} from './directives/validators';
 import {StringMapWrapper} from './facade/collection';
-import {isBlank, isPresent, isPromise, isString} from './facade/lang';
+import {isBlank, isPresent, isString} from './facade/lang';
 import {AbstractControl} from './model';
+import {isPromise} from './private_import_core';
+
 
 
 /**