diff --git a/extensions/amp-access/0.1/test/test-amp-access-client.js b/extensions/amp-access/0.1/test/test-amp-access-client.js
index 1e00805674d7..841b97236fbf 100644
--- a/extensions/amp-access/0.1/test/test-amp-access-client.js
+++ b/extensions/amp-access/0.1/test/test-amp-access-client.js
@@ -31,7 +31,7 @@ describes.realWin('AccessClientAdapter', {
 
   beforeEach(() => {
     ampdoc = env.ampdoc;
-    clock = lolex.install();
+    clock = lolex.install({target: ampdoc.win});
 
     validConfig = {
       'authorization': 'https://acme.com/a?rid=READER_ID',
@@ -190,8 +190,7 @@ describes.realWin('AccessClientAdapter', {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should time out XHR fetch', () => {
+      it('should time out XHR fetch', () => {
         contextMock.expects('buildUrl')
             .withExactArgs(
                 'https://acme.com/a?rid=READER_ID',
diff --git a/extensions/amp-access/0.1/test/test-amp-access-server-jwt.js b/extensions/amp-access/0.1/test/test-amp-access-server-jwt.js
index 4ffa43813fff..fcc295d2d6a5 100644
--- a/extensions/amp-access/0.1/test/test-amp-access-server-jwt.js
+++ b/extensions/amp-access/0.1/test/test-amp-access-server-jwt.js
@@ -34,7 +34,7 @@ describes.realWin('AccessServerJwtAdapter', {amp: true}, env => {
   beforeEach(() => {
     win = env.win;
     ampdoc = env.ampdoc;
-    clock = lolex.install();
+    clock = lolex.install({target: win});
 
     validConfig = {
       'authorization': 'https://acme.com/a?rid=READER_ID',
@@ -277,8 +277,7 @@ describes.realWin('AccessServerJwtAdapter', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should fail when authorize-and-fill times out', () => {
+      it('should fail when authorize-and-fill times out', () => {
         adapter.serviceUrl_ = 'http://localhost:8000/af';
         const authdata = {};
         const jwt = {'amp_authdata': authdata};
@@ -408,8 +407,7 @@ describes.realWin('AccessServerJwtAdapter', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should fail when JWT fetch times out', () => {
+      it('should fail when JWT fetch times out', () => {
         contextMock.expects('buildUrl')
             .withExactArgs(
                 'https://acme.com/a?rid=READER_ID',
diff --git a/extensions/amp-access/0.1/test/test-amp-access-server.js b/extensions/amp-access/0.1/test/test-amp-access-server.js
index 0fff6bcf70e0..cf9b9f5b3607 100644
--- a/extensions/amp-access/0.1/test/test-amp-access-server.js
+++ b/extensions/amp-access/0.1/test/test-amp-access-server.js
@@ -33,7 +33,7 @@ describes.realWin('AccessServerAdapter', {amp: true}, env => {
     win = env.win;
     document = win.document;
     ampdoc = env.ampdoc;
-    clock = lolex.install();
+    clock = lolex.install({target: win});
 
     validConfig = {
       'authorization': 'https://acme.com/a?rid=READER_ID',
@@ -232,8 +232,7 @@ describes.realWin('AccessServerAdapter', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should time out XHR fetch', () => {
+      it('should time out XHR fetch', () => {
         adapter.serviceUrl_ = 'http://localhost:8000/af';
         contextMock.expects('collectUrlVars')
             .withExactArgs(
diff --git a/extensions/amp-ad/0.1/test/test-amp-ad-3p-impl.js b/extensions/amp-ad/0.1/test/test-amp-ad-3p-impl.js
index 496654b83c50..3e9d79637810 100644
--- a/extensions/amp-ad/0.1/test/test-amp-ad-3p-impl.js
+++ b/extensions/amp-ad/0.1/test/test-amp-ad-3p-impl.js
@@ -291,9 +291,8 @@ describes.realWin('amp-ad-3p-impl', {
       expect(ad3p.renderOutsideViewport()).to.equal(1.25);
     });
 
-    // TODO(lannka, #12486): Make this test work with lolex v2.
-    it.skip('should only allow rendering one ad per second', function* () {
-      const clock = lolex.install();
+    it('should only allow rendering one ad per second', function* () {
+      const clock = lolex.install({target: win});
       const ad3p2 = createAmpAd(win);
       expect(ad3p.renderOutsideViewport()).to.equal(3);
       expect(ad3p2.renderOutsideViewport()).to.equal(3);
diff --git a/extensions/amp-ad/0.1/test/test-concurrent-load.js b/extensions/amp-ad/0.1/test/test-concurrent-load.js
index 2f35eacd476c..394e1743e87f 100644
--- a/extensions/amp-ad/0.1/test/test-concurrent-load.js
+++ b/extensions/amp-ad/0.1/test/test-concurrent-load.js
@@ -65,15 +65,15 @@ describes.realWin('concurrent-load', {}, env => {
     }
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  describe.skip('incrementLoadingAds', () => {
+  describe('incrementLoadingAds', () => {
 
     let win;
     let clock;
 
     beforeEach(() => {
       win = env.win;
-      clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+      clock = lolex.install({
+        target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
       installTimerService(win);
     });
 
diff --git a/extensions/amp-analytics/0.1/test/test-events.js b/extensions/amp-analytics/0.1/test/test-events.js
index 596aa05cb309..adaf481aec8a 100644
--- a/extensions/amp-analytics/0.1/test/test-events.js
+++ b/extensions/amp-analytics/0.1/test/test-events.js
@@ -542,7 +542,7 @@ describes.realWin('Events', {amp: 1}, env => {
     let tracker;
 
     beforeEach(() => {
-      clock = lolex.install(root.ampdoc.win);
+      clock = lolex.install({target: root.ampdoc.win});
       tracker = root.getTracker('timer', TimerEventTracker);
     });
 
@@ -685,8 +685,7 @@ describes.realWin('Events', {amp: 1}, env => {
       });
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('timers started and stopped by the same event on the same target'
+    it('timers started and stopped by the same event on the same target'
         + ' do not have race condition problems', () => {
       const fn1 = sandbox.stub();
       tracker.add(analyticsElement, 'timer', {timerSpec: {
@@ -740,8 +739,7 @@ describes.realWin('Events', {amp: 1}, env => {
       expect(fn2.args[0][0].type).to.equal('timer');
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('fires on the appropriate interval', () => {
+    it('fires on the appropriate interval', () => {
       const fn1 = sandbox.stub();
       tracker.add(analyticsElement, 'timer', {timerSpec: {
         interval: 10,
@@ -791,8 +789,7 @@ describes.realWin('Events', {amp: 1}, env => {
       expect(fn1.args[0][0].type).to.equal('timer');
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('stops firing after the maxTimerLength is exceeded', () => {
+    it('stops firing after the maxTimerLength is exceeded', () => {
       const fn1 = sandbox.stub();
       tracker.add(analyticsElement, 'timer', {timerSpec: {
         interval: 10,
@@ -861,8 +858,7 @@ describes.realWin('Events', {amp: 1}, env => {
       expect(tracker.getTrackedTimerKeys()).to.have.length(1);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should unlisten tracker', () => {
+    it('should unlisten tracker', () => {
       const fn1 = sandbox.stub();
       const u1 = tracker.add(analyticsElement, 'timer', {timerSpec: {
         interval: 10,
@@ -889,8 +885,7 @@ describes.realWin('Events', {amp: 1}, env => {
       expect(countIntervals()).to.equal(0);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should dispose all trackers', () => {
+    it('should dispose all trackers', () => {
       const fn1 = sandbox.stub();
       tracker.add(analyticsElement, 'timer', {timerSpec: {
         interval: 10,
@@ -911,8 +906,7 @@ describes.realWin('Events', {amp: 1}, env => {
       expect(countIntervals()).to.equal(0);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should create events with timer vars', () => {
+    it('should create events with timer vars', () => {
       const handler = sandbox.stub();
       tracker.add(analyticsElement, 'timer', {timerSpec: {
         interval: 3,
diff --git a/extensions/amp-analytics/0.1/test/test-requests.js b/extensions/amp-analytics/0.1/test/test-requests.js
index 442f80e9efc3..c1a42a7bc827 100644
--- a/extensions/amp-analytics/0.1/test/test-requests.js
+++ b/extensions/amp-analytics/0.1/test/test-requests.js
@@ -29,7 +29,7 @@ describes.realWin('Requests', {amp: 1}, env => {
   beforeEach(() => {
     installVariableService(env.win);
     ampdoc = env.ampdoc;
-    clock = lolex.install();
+    clock = lolex.install({target: ampdoc.win});
     preconnectSpy = sandbox.spy();
     preconnect = {
       url: preconnectSpy,
@@ -40,8 +40,7 @@ describes.realWin('Requests', {amp: 1}, env => {
     clock.uninstall();
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  describe.skip('RequestHandler', () => {
+  describe('RequestHandler', () => {
     describe('batch Delay', () => {
       it('maxDelay should  be a number', () => {
         const r1 = {'baseUrl': 'r1', 'maxDelay': 1};
diff --git a/test/functional/test-ad-cid.js b/test/functional/test-ad-cid.js
index 2c4fe13d6275..f71f7a1c9a0a 100644
--- a/test/functional/test-ad-cid.js
+++ b/test/functional/test-ad-cid.js
@@ -36,7 +36,8 @@ describes.realWin('ad-cid', {amp: true}, env => {
   beforeEach(() => {
     win = env.win;
     sandbox = env.sandbox;
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install({
+      target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
     element = env.win.document.createElement('amp-ad');
     element.setAttribute('type', '_ping_');
     const ampdoc = env.ampdoc;
@@ -89,8 +90,7 @@ describes.realWin('ad-cid', {amp: true}, env => {
     });
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should return on timeout', () => {
+  it('should return on timeout', () => {
     config.clientIdScope = cidScope;
     sandbox.stub(cidService, 'get').callsFake(() => {
       return Services.timerFor(win).promise(2000);
diff --git a/test/functional/test-cid.js b/test/functional/test-cid.js
index f1a6f015db04..269cc4381e2d 100644
--- a/test/functional/test-cid.js
+++ b/test/functional/test-cid.js
@@ -723,7 +723,8 @@ describes.realWin('cid', {amp: true}, env => {
     win = env.win;
     ampdoc = env.ampdoc;
     sandbox = env.sandbox;
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install({
+      target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
     cid = cidServiceForDocForTesting(ampdoc);
   });
 
@@ -758,8 +759,7 @@ describes.realWin('cid', {amp: true}, env => {
         .to.eventually.equal('cid-from-viewer');
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('get method should time out when in Viewer', function *() {
+  it('get method should time out when in Viewer', function *() {
     win.parent = {};
     stubServiceForDoc(sandbox, ampdoc, 'viewer', 'sendMessageAwaitResponse')
         .returns(new Promise(() => {}));
@@ -795,8 +795,7 @@ describes.realWin('cid', {amp: true}, env => {
       setCookie(win, '_ga', '', 0);
     });
 
-    // TODO(lannka, #12486): Make this test work with lolex v2.
-    it.skip('should use cid api on pub origin if opted in', () => {
+    it('should use cid api on pub origin if opted in', () => {
       const getScopedCidStub = sandbox.stub(cid.cidApi_, 'getScopedCid');
       getScopedCidStub.returns(Promise.resolve('cid-from-api'));
       return cid.get({
@@ -811,8 +810,7 @@ describes.realWin('cid', {amp: true}, env => {
       });
     });
 
-    // TODO(lannka, #12486): Make this test work with lolex v2.
-    it.skip('should fallback to cookie if cid api returns nothing', () => {
+    it('should fallback to cookie if cid api returns nothing', () => {
       sandbox.stub(cid.cidApi_, 'getScopedCid').returns(Promise.resolve());
       return cid.get({
         scope: 'AMP_ECID_GOOGLE',
diff --git a/test/functional/test-custom-element.js b/test/functional/test-custom-element.js
index 3cd85c153e49..a790144ec959 100644
--- a/test/functional/test-custom-element.js
+++ b/test/functional/test-custom-element.js
@@ -106,7 +106,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       win = env.win;
       doc = win.document;
       ampdoc = env.ampdoc;
-      clock = lolex.install();
+      clock = lolex.install({target: win});
       resources = Services.resourcesForDoc(doc);
       resources.isBuildOn_ = true;
       resourcesMock = sandbox.mock(resources);
@@ -362,8 +362,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       expect(element.isBuilt()).to.equal(false);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('Element - re-upgrade to new direct instance', () => {
+    it('Element - re-upgrade to new direct instance', () => {
       const element = new ElementClass();
       expect(element.isUpgraded()).to.equal(false);
       const newImpl = new TestElement(element);
@@ -375,8 +374,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       expect(element.upgradeDelayMs_).to.equal(0);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('Element - re-upgrade to new promised instance', () => {
+    it('Element - re-upgrade to new promised instance', () => {
       const element = new ElementClass();
       expect(element.isUpgraded()).to.equal(false);
       const oldImpl = element.implementation_;
@@ -544,8 +542,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       });
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('Element - buildCallback cannot be called twice', () => {
+    it('Element - buildCallback cannot be called twice', () => {
       const element = new ElementClass();
       expect(element.isBuilt()).to.equal(false);
       expect(testElementBuildCallback).to.have.not.been.called;
@@ -717,8 +714,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       expect(testElementLayoutCallback).to.have.not.been.called;
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('Element - layoutCallback', () => {
+    it('Element - layoutCallback', () => {
       const element = new ElementClass();
       element.setAttribute('layout', 'fill');
       container.appendChild(element);
@@ -839,8 +835,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       });
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should dequeue all actions after build', () => {
+    it('should dequeue all actions after build', () => {
       const element = new ElementClass();
       const handler = sandbox.spy();
       element.implementation_.executeAction = handler;
@@ -1513,7 +1508,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
     beforeEach(() => {
       win = env.win;
       doc = win.document;
-      clock = lolex.install();
+      clock = lolex.install({target: win});
       ElementClass = doc.registerElement('amp-test-loader', {
         prototype: createAmpElementProtoForTesting(
             win, 'amp-test-loader', TestElement),
@@ -1715,8 +1710,7 @@ describes.realWin('CustomElement', {amp: true}, env => {
       expect(toggle).to.have.not.been.called;
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should turn on when enters viewport', () => {
+    it('should turn on when enters viewport', () => {
       stubInA4A(false);
       const toggle = sandbox.spy(element, 'toggleLoading_');
       element.viewportCallback(true);
diff --git a/test/functional/test-jank-meter.js b/test/functional/test-jank-meter.js
index e4adfb889948..bf943b01f63d 100644
--- a/test/functional/test-jank-meter.js
+++ b/test/functional/test-jank-meter.js
@@ -26,7 +26,8 @@ describes.realWin('jank-meter', {}, env => {
 
   beforeEach(() => {
     win = env.win;
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install({
+      target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
 
     meter = new JankMeter(win);
     meter.perf_ = {
@@ -40,8 +41,7 @@ describes.realWin('jank-meter', {}, env => {
     clock.uninstall();
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should use first schedule time when scheduled ' +
+  it('should use first schedule time when scheduled ' +
       'multiple times ', () => {
     meter.onScheduled();
     clock.tick(5);
@@ -52,8 +52,7 @@ describes.realWin('jank-meter', {}, env => {
     expect(meter.badFrameCnt_).to.equal(1);
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should count bad frames correctly', () => {
+  it('should count bad frames correctly', () => {
     runTask(16);
     expect(meter.totalFrameCnt_).to.equal(1);
     expect(meter.badFrameCnt_).to.equal(0);
diff --git a/test/functional/test-layout-delay-meter.js b/test/functional/test-layout-delay-meter.js
index 8b6f70042936..01531990fc6a 100644
--- a/test/functional/test-layout-delay-meter.js
+++ b/test/functional/test-layout-delay-meter.js
@@ -37,7 +37,8 @@ describes.realWin('layout-delay-meter', {
     installPerformanceService(win);
     const perf = Services.performanceFor(win);
     sandbox.stub(perf, 'isPerformanceTrackingOn').callsFake(() => true);
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install({
+      target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
     tickSpy = sandbox.spy(perf, 'tickDelta');
 
     meter = new LayoutDelayMeter(win, 2);
@@ -47,8 +48,7 @@ describes.realWin('layout-delay-meter', {
     clock.uninstall();
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should tick when there is a delay', () => {
+  it('should tick when there is a delay', () => {
     clock.tick(100);
     meter.enterViewport(); // first time in viewport
     clock.tick(100);
diff --git a/test/functional/test-performance.js b/test/functional/test-performance.js
index 76d719f73dfc..78e9295cee48 100644
--- a/test/functional/test-performance.js
+++ b/test/functional/test-performance.js
@@ -32,7 +32,8 @@ describes.realWin('performance', {amp: true}, env => {
     win = env.win;
     sandbox = env.sandbox;
     ampdoc = env.ampdoc;
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install({
+      target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
     installPerformanceService(env.win);
     perf = Services.performanceFor(env.win);
   });
@@ -105,8 +106,7 @@ describes.realWin('performance', {amp: true}, env => {
       expect(perf.events_.length).to.equal(50);
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should add default optional relative start time on the ' +
+    it('should add default optional relative start time on the ' +
        'queued tick event', () => {
       clock.tick(150);
       perf.tick('start0');
@@ -117,8 +117,7 @@ describes.realWin('performance', {amp: true}, env => {
       });
     });
 
-    // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-    it.skip('should drop events in the head of the queue', () => {
+    it('should drop events in the head of the queue', () => {
       const tickTime = 100;
       clock.tick(tickTime);
 
@@ -197,8 +196,7 @@ describes.realWin('performance', {amp: true}, env => {
 
     describe('channel established', () => {
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should flush events when channel is ready', () => {
+      it('should flush events when channel is ready', () => {
         sandbox.stub(viewer, 'getParam').withArgs('csi').returns(null);
         sandbox.stub(viewer, 'whenMessagingReady')
             .returns(Promise.resolve());
@@ -297,8 +295,7 @@ describes.realWin('performance', {amp: true}, env => {
         expect(tickDeltaStub.firstCall.args[1]).to.equal(0);
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should calculate after visible', () => {
+      it('should calculate after visible', () => {
         perf.coreServicesAvailable();
         firstVisibleTime = 5;
 
@@ -309,8 +306,7 @@ describes.realWin('performance', {amp: true}, env => {
         expect(tickDeltaStub.firstCall.args[1]).to.equal(5);
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should be zero after visible but for earlier event', () => {
+      it('should be zero after visible but for earlier event', () => {
         perf.coreServicesAvailable();
         firstVisibleTime = 5;
 
@@ -374,8 +370,7 @@ describes.realWin('performance', {amp: true}, env => {
             .returns(Promise.resolve());
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should forward all queued tick events', () => {
+      it('should forward all queued tick events', () => {
         perf.tick('start0');
         clock.tick(1);
         perf.tick('start1');
@@ -412,8 +407,7 @@ describes.realWin('performance', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should forward tick events', () => {
+      it('should forward tick events', () => {
         return perf.coreServicesAvailable().then(() => {
           clock.tick(100);
           perf.tick('start0');
@@ -538,8 +532,7 @@ describes.realWin('performance', {amp: true}, env => {
         return perf.coreServicesAvailable();
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should call prerenderComplete on viewer', () => {
+      it('should call prerenderComplete on viewer', () => {
         clock.tick(100);
         whenFirstVisibleResolve();
         sandbox.stub(viewer, 'getParam').withArgs('csi').returns('1');
@@ -557,8 +550,7 @@ describes.realWin('performance', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should call prerenderComplete on viewer even if csi is ' +
+      it('should call prerenderComplete on viewer even if csi is ' +
         'off', () => {
         clock.tick(100);
         whenFirstVisibleResolve();
@@ -573,8 +565,7 @@ describes.realWin('performance', {amp: true}, env => {
         });
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should tick `pc` with delta=400 when user request document ' +
+      it('should tick `pc` with delta=400 when user request document ' +
          'to be visible before before first viewport completion', () => {
         clock.tick(100);
         whenFirstVisibleResolve();
@@ -620,8 +611,7 @@ describes.realWin('performance', {amp: true}, env => {
         perf.coreServicesAvailable();
       });
 
-      // TODO(dvoytenko, #12486): Make this test work with lolex v2.
-      it.skip('should call prerenderComplete on viewer', () => {
+      it('should call prerenderComplete on viewer', () => {
         sandbox.stub(viewer, 'getParam').withArgs('csi').returns('1');
         sandbox.stub(viewer, 'isEmbedded').returns(true);
         clock.tick(300);
diff --git a/test/functional/test-position-observer.js b/test/functional/test-position-observer.js
index dad485d11468..17646c764b26 100644
--- a/test/functional/test-position-observer.js
+++ b/test/functional/test-position-observer.js
@@ -40,7 +40,7 @@ describes.realWin('PositionObserver', {amp: 1}, env => {
     let elem1;
     let clock;
     beforeEach(() => {
-      clock = lolex.install();
+      clock = lolex.install({target: ampdoc.win});
       posOb = new PositionObserver(ampdoc);
       sandbox.stub(posOb.vsync_, 'measure').callsFake(callback => {
         win.setTimeout(callback, 1);
@@ -88,8 +88,7 @@ describes.realWin('PositionObserver', {amp: 1}, env => {
       });
     });
 
-    // TODO(zhouyx, #12486): Make this test work with lolex v2.
-    describe.skip('update position info at correct time', () => {
+    describe('update position info at correct time', () => {
       let top;
       beforeEach(() => {
         top = 0;
@@ -134,8 +133,7 @@ describes.realWin('PositionObserver', {amp: 1}, env => {
       });
     });
 
-    // TODO(zhouyx, #12486): Make this test work with lolex v2.
-    describe.skip('should provide correct position data', () => {
+    describe('should provide correct position data', () => {
       let top;
       beforeEach(() => {
         top = 0;
diff --git a/test/functional/test-yield.js b/test/functional/test-yield.js
index f4851edc6e3f..b46c794a273b 100644
--- a/test/functional/test-yield.js
+++ b/test/functional/test-yield.js
@@ -24,15 +24,15 @@ describes.realWin('yield', {}, env => {
 
   beforeEach(() => {
     win = env.win;
-    clock = lolex.install({toFake: ['Date', 'setTimeout', 'clearTimeout']});
+    clock = lolex.install(
+        {target: win, toFake: ['Date', 'setTimeout', 'clearTimeout']});
   });
 
   afterEach(() => {
     clock.uninstall();
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should work with nested promises', function* () {
+  it('should work with nested promises', function* () {
     let value = false;
 
     const nestPromise = level => {
@@ -51,8 +51,7 @@ describes.realWin('yield', {}, env => {
     expect(value).to.be.true;
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should work with promise chain', function* () {
+  it('should work with promise chain', function* () {
     let value;
 
     const chainPromise = Promise.resolve();
@@ -67,8 +66,7 @@ describes.realWin('yield', {}, env => {
     expect(value).to.be.true;
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should work with promise inside setTimeout', function* () {
+  it('should work with promise inside setTimeout', function* () {
     let value;
     win.setTimeout(() => {
       value = false;
@@ -84,8 +82,7 @@ describes.realWin('yield', {}, env => {
     expect(value).to.be.true;
   });
 
-  // TODO(lannka, #12486): Make this test work with lolex v2.
-  it.skip('should work with manually resolved promise inside ' +
+  it('should work with manually resolved promise inside ' +
       'setTimeout', function* () {
     let value;
     let resolver;