diff --git a/.eslintrc.json b/.eslintrc.json
index 058fd6f03..dc4a0b0a5 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -42,6 +42,7 @@
     "jsdoc/require-param-description": 0,
     "jsdoc/require-property-description": 0,
     "jsdoc/require-param-type": 0,
+    "jsdoc/tag-lines": 0,
     "jsdoc/check-param-names": [
       "error",
       {
diff --git a/integration/test/ParseUserTest.js b/integration/test/ParseUserTest.js
index 64b6f2bd9..2704c34b8 100644
--- a/integration/test/ParseUserTest.js
+++ b/integration/test/ParseUserTest.js
@@ -148,6 +148,27 @@ describe('Parse User', () => {
     expect(sessions[1].get('sessionToken')).toBe(installationUser.getSessionToken());
   });
 
+  it('can login with userId', async () => {
+    Parse.User.enableUnsafeCurrentUser();
+
+    const user = await Parse.User.signUp('parsetest', 'parse', { code: 'red' });
+    assert.equal(Parse.User.current(), user);
+    await Parse.User.logOut();
+    assert(!Parse.User.current());
+
+    const newUser = await Parse.User.loginAs(user.id);
+    assert.equal(Parse.User.current(), newUser);
+    assert(newUser);
+    assert.equal(user.id, newUser.id);
+    assert.equal(user.get('code'), 'red');
+
+    await Parse.User.logOut();
+    assert(!Parse.User.current());
+    await expectAsync(Parse.User.loginAs('garbage')).toBeRejectedWithError(
+      'user not found'
+    );
+  });
+
   it('can become a user', done => {
     Parse.User.enableUnsafeCurrentUser();
     let session = null;
@@ -782,6 +803,16 @@ describe('Parse User', () => {
     expect(user.doSomething()).toBe(5);
   });
 
+  it('can loginAs user with subclass static', async () => {
+    Parse.User.enableUnsafeCurrentUser();
+
+    let user = await CustomUser.signUp('username', 'password');
+
+    user = await CustomUser.loginAs(user.id);
+    expect(user instanceof CustomUser).toBe(true);
+    expect(user.doSomething()).toBe(5);
+  });
+
   it('can get user (me) with subclass static', async () => {
     Parse.User.enableUnsafeCurrentUser();
 
diff --git a/src/ParseUser.js b/src/ParseUser.js
index 1bd9c3780..d2014f1ac 100644
--- a/src/ParseUser.js
+++ b/src/ParseUser.js
@@ -653,6 +653,25 @@ class ParseUser extends ParseObject {
     return user.logIn(options);
   }
 
+  /**
+   * Logs in a user with an objectId. On success, this saves the session
+   * to disk, so you can retrieve the currently logged in user using
+   * <code>current</code>.
+   *
+   * @param {string} userId The objectId for the user.
+   * @static
+   * @returns {Promise} A promise that is fulfilled with the user when
+   *     the login completes.
+   */
+  static loginAs(userId: string) {
+    if (!userId) {
+      throw new ParseError(ParseError.USERNAME_MISSING, 'Cannot log in as user with an empty user id');
+    }
+    const controller = CoreManager.getUserController();
+    const user = new this();
+    return controller.loginAs(user, userId);
+  }
+
   /**
    * Logs in a user with a session token. On success, this saves the session
    * to disk, so you can retrieve the currently logged in user using
@@ -1097,6 +1116,18 @@ const DefaultController = {
     );
   },
 
+  loginAs(user: ParseUser, userId: string): Promise<ParseUser> {
+    const RESTController = CoreManager.getRESTController();
+    return RESTController.request('POST', 'loginAs', { userId }, { useMasterKey: true }).then(response => {
+      user._finishFetch(response);
+      user._setExisted(true);
+      if (!canUseCurrentUser) {
+        return Promise.resolve(user);
+      }
+      return DefaultController.setCurrentUser(user);
+    });
+  },
+
   become(user: ParseUser, options: RequestOptions): Promise<ParseUser> {
     const RESTController = CoreManager.getRESTController();
     return RESTController.request('GET', 'users/me', {}, options).then(response => {
diff --git a/src/__tests__/ParseUser-test.js b/src/__tests__/ParseUser-test.js
index 4f030123a..f671149c3 100644
--- a/src/__tests__/ParseUser-test.js
+++ b/src/__tests__/ParseUser-test.js
@@ -360,6 +360,73 @@ describe('ParseUser', () => {
     });
   });
 
+  it('does not allow loginAs without id', (done) => {
+    try {
+      ParseUser.loginAs(null, null);
+    } catch (e) {
+      expect(e.message).toBe('Cannot log in as user with an empty user id')
+      done();
+    }
+  });
+
+  it('can login as a user with an objectId', async () => {
+    ParseUser.disableUnsafeCurrentUser();
+    ParseUser._clearCache();
+    CoreManager.setRESTController({
+      request(method, path, body, options) {
+        expect(method).toBe('POST');
+        expect(path).toBe('loginAs');
+        expect(body.userId).toBe('uid4');
+        expect(options.useMasterKey).toBe(true);
+
+        return Promise.resolve(
+          {
+            objectId: 'uid4',
+            username: 'username',
+            sessionToken: '123abc',
+          },
+          200
+        );
+      },
+      ajax() {},
+    });
+
+    const user = await ParseUser.loginAs('uid4');
+    expect(user.id).toBe('uid4');
+    expect(user.isCurrent()).toBe(false);
+    expect(user.existed()).toBe(true);
+  });
+
+  it('can loginAs a user with async storage', async () => {
+    const currentStorage = CoreManager.getStorageController();
+    CoreManager.setStorageController(mockAsyncStorage);
+    ParseUser.enableUnsafeCurrentUser();
+    ParseUser._clearCache();
+    CoreManager.setRESTController({
+      request(method, path, body, options) {
+        expect(method).toBe('POST');
+        expect(path).toBe('loginAs');
+        expect(body.userId).toBe('uid5');
+        expect(options.useMasterKey).toBe(true);
+        return Promise.resolve(
+          {
+            objectId: 'uid5',
+            username: 'username',
+            sessionToken: '123abc',
+          },
+          200
+        );
+      },
+      ajax() {},
+    });
+
+    const user = await ParseUser.loginAs('uid5');
+    expect(user.id).toBe('uid5');
+    expect(user.isCurrent()).toBe(true);
+    expect(user.existed()).toBe(true);
+    CoreManager.setStorageController(currentStorage);
+  });
+
   it('can become a user with a session token', done => {
     ParseUser.enableUnsafeCurrentUser();
     ParseUser._clearCache();