diff --git a/packages/react-devtools-shared/src/__tests__/profilingHostRoot-test.js b/packages/react-devtools-shared/src/__tests__/profilingHostRoot-test.js
new file mode 100644
index 0000000000000..a37401eb4a06e
--- /dev/null
+++ b/packages/react-devtools-shared/src/__tests__/profilingHostRoot-test.js
@@ -0,0 +1,144 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+describe('profiling HostRoot', () => {
+  let React;
+  let ReactDOM;
+  let Scheduler;
+  let store: Store;
+  let utils;
+  let getEffectDurations;
+
+  let effectDurations;
+  let passiveEffectDurations;
+
+  beforeEach(() => {
+    utils = require('./utils');
+    utils.beforeEachProfiling();
+
+    getEffectDurations = require('../backend/utils').getEffectDurations;
+
+    store = global.store;
+
+    React = require('react');
+    ReactDOM = require('react-dom');
+    Scheduler = require('scheduler');
+
+    effectDurations = [];
+    passiveEffectDurations = [];
+
+    // This is the DevTools hook installed by the env.beforEach()
+    // The hook is installed as a read-only property on the window,
+    // so for our test purposes we can just override the commit hook.
+    const hook = global.__REACT_DEVTOOLS_GLOBAL_HOOK__;
+    hook.onPostCommitFiberRoot = function onPostCommitFiberRoot(
+      rendererID,
+      root,
+    ) {
+      const {effectDuration, passiveEffectDuration} = getEffectDurations(root);
+      effectDurations.push(effectDuration);
+      passiveEffectDurations.push(passiveEffectDuration);
+    };
+  });
+
+  it('should expose passive and layout effect durations for render()', () => {
+    function App() {
+      React.useEffect(() => {
+        Scheduler.unstable_advanceTime(10);
+      });
+      React.useLayoutEffect(() => {
+        Scheduler.unstable_advanceTime(100);
+      });
+      return null;
+    }
+
+    utils.act(() => store.profilerStore.startProfiling());
+    utils.act(() => {
+      const container = document.createElement('div');
+      ReactDOM.render(<App />, container);
+    });
+    utils.act(() => store.profilerStore.stopProfiling());
+
+    expect(effectDurations).toHaveLength(1);
+    const effectDuration = effectDurations[0];
+    expect(effectDuration === null || effectDuration === 100).toBe(true);
+    expect(passiveEffectDurations).toHaveLength(1);
+    const passiveEffectDuration = passiveEffectDurations[0];
+    expect(passiveEffectDuration === null || passiveEffectDuration === 10).toBe(
+      true,
+    );
+  });
+
+  it('should expose passive and layout effect durations for createRoot()', () => {
+    function App() {
+      React.useEffect(() => {
+        Scheduler.unstable_advanceTime(10);
+      });
+      React.useLayoutEffect(() => {
+        Scheduler.unstable_advanceTime(100);
+      });
+      return null;
+    }
+
+    utils.act(() => store.profilerStore.startProfiling());
+    utils.act(() => {
+      const container = document.createElement('div');
+      const root = ReactDOM.unstable_createRoot(container);
+      root.render(<App />);
+    });
+    utils.act(() => store.profilerStore.stopProfiling());
+
+    expect(effectDurations).toHaveLength(1);
+    const effectDuration = effectDurations[0];
+    expect(effectDuration === null || effectDuration === 100).toBe(true);
+    expect(passiveEffectDurations).toHaveLength(1);
+    const passiveEffectDuration = passiveEffectDurations[0];
+    expect(passiveEffectDuration === null || passiveEffectDuration === 10).toBe(
+      true,
+    );
+  });
+
+  it('should properly reset passive and layout effect durations between commits', () => {
+    function App({shouldCascade}) {
+      const [, setState] = React.useState(false);
+      React.useEffect(() => {
+        Scheduler.unstable_advanceTime(10);
+      });
+      React.useLayoutEffect(() => {
+        Scheduler.unstable_advanceTime(100);
+      });
+      React.useLayoutEffect(() => {
+        if (shouldCascade) {
+          setState(true);
+        }
+      }, [shouldCascade]);
+      return null;
+    }
+
+    const container = document.createElement('div');
+    const root = ReactDOM.unstable_createRoot(container);
+
+    utils.act(() => store.profilerStore.startProfiling());
+    utils.act(() => root.render(<App />));
+    utils.act(() => root.render(<App shouldCascade={true} />));
+    utils.act(() => store.profilerStore.stopProfiling());
+
+    expect(effectDurations).toHaveLength(3);
+    expect(passiveEffectDurations).toHaveLength(3);
+
+    for (let i = 0; i < effectDurations.length; i++) {
+      const effectDuration = effectDurations[i];
+      expect(effectDuration === null || effectDuration === 100).toBe(true);
+      const passiveEffectDuration = passiveEffectDurations[i];
+      expect(
+        passiveEffectDuration === null || passiveEffectDuration === 10,
+      ).toBe(true);
+    }
+  });
+});
diff --git a/packages/react-devtools-shared/src/backend/legacy/renderer.js b/packages/react-devtools-shared/src/backend/legacy/renderer.js
index 08cbfe340fb6f..fcc7895356aae 100644
--- a/packages/react-devtools-shared/src/backend/legacy/renderer.js
+++ b/packages/react-devtools-shared/src/backend/legacy/renderer.js
@@ -1012,6 +1012,9 @@ export function attach(
   const handleCommitFiberUnmount = () => {
     throw new Error('handleCommitFiberUnmount not supported by this renderer');
   };
+  const handlePostCommitFiberRoot = () => {
+    throw new Error('handlePostCommitFiberRoot not supported by this renderer');
+  };
   const overrideSuspense = () => {
     throw new Error('overrideSuspense not supported by this renderer');
   };
@@ -1082,6 +1085,7 @@ export function attach(
     getProfilingData,
     handleCommitFiberRoot,
     handleCommitFiberUnmount,
+    handlePostCommitFiberRoot,
     inspectElement,
     logElementToConsole,
     overrideSuspense,
diff --git a/packages/react-devtools-shared/src/backend/renderer.js b/packages/react-devtools-shared/src/backend/renderer.js
index c61edb45daa65..09042d0446b29 100644
--- a/packages/react-devtools-shared/src/backend/renderer.js
+++ b/packages/react-devtools-shared/src/backend/renderer.js
@@ -42,6 +42,7 @@ import {
   copyWithDelete,
   copyWithRename,
   copyWithSet,
+  getEffectDurations,
 } from './utils';
 import {
   __DEBUG__,
@@ -369,6 +370,7 @@ export function getInternalReactConstants(
     LegacyHiddenComponent,
     MemoComponent,
     OffscreenComponent,
+    Profiler,
     ScopeComponent,
     SimpleMemoComponent,
     SuspenseComponent,
@@ -442,6 +444,8 @@ export function getInternalReactConstants(
         return 'Scope';
       case SuspenseListComponent:
         return 'SuspenseList';
+      case Profiler:
+        return 'Profiler';
       default:
         const typeSymbol = getTypeSymbol(type);
 
@@ -2154,25 +2158,6 @@ export function attach(
         // Checking root.memoizedInteractions handles multi-renderer edge-case-
         // where some v16 renderers support profiling and others don't.
         if (isProfiling && root.memoizedInteractions != null) {
-          // Profiling durations are only available for certain builds.
-          // If available, they'll be stored on the HostRoot.
-          let effectDuration = null;
-          let passiveEffectDuration = null;
-          const hostRoot = root.current;
-          if (hostRoot != null) {
-            const stateNode = hostRoot.stateNode;
-            if (stateNode != null) {
-              effectDuration =
-                stateNode.effectDuration != null
-                  ? stateNode.effectDuration
-                  : null;
-              passiveEffectDuration =
-                stateNode.passiveEffectDuration != null
-                  ? stateNode.passiveEffectDuration
-                  : null;
-            }
-          }
-
           // If profiling is active, store commit time and duration, and the current interactions.
           // The frontend may request this information after profiling has stopped.
           currentCommitProfilingMetadata = {
@@ -2187,8 +2172,8 @@ export function attach(
             ),
             maxActualDuration: 0,
             priorityLevel: null,
-            effectDuration,
-            passiveEffectDuration,
+            effectDuration: null,
+            passiveEffectDuration: null,
           };
         }
 
@@ -2206,6 +2191,19 @@ export function attach(
     recordUnmount(fiber, false);
   }
 
+  function handlePostCommitFiberRoot(root) {
+    const isProfilingSupported = root.memoizedInteractions != null;
+    if (isProfiling && isProfilingSupported) {
+      if (currentCommitProfilingMetadata !== null) {
+        const {effectDuration, passiveEffectDuration} = getEffectDurations(
+          root,
+        );
+        currentCommitProfilingMetadata.effectDuration = effectDuration;
+        currentCommitProfilingMetadata.passiveEffectDuration = passiveEffectDuration;
+      }
+    }
+  }
+
   function handleCommitFiberRoot(root, priorityLevel) {
     const current = root.current;
     const alternate = current.alternate;
@@ -2227,23 +2225,6 @@ export function attach(
     const isProfilingSupported = root.memoizedInteractions != null;
 
     if (isProfiling && isProfilingSupported) {
-      // Profiling durations are only available for certain builds.
-      // If available, they'll be stored on the HostRoot.
-      let effectDuration = null;
-      let passiveEffectDuration = null;
-      const hostRoot = root.current;
-      if (hostRoot != null) {
-        const stateNode = hostRoot.stateNode;
-        if (stateNode != null) {
-          effectDuration =
-            stateNode.effectDuration != null ? stateNode.effectDuration : null;
-          passiveEffectDuration =
-            stateNode.passiveEffectDuration != null
-              ? stateNode.passiveEffectDuration
-              : null;
-        }
-      }
-
       // If profiling is active, store commit time and duration, and the current interactions.
       // The frontend may request this information after profiling has stopped.
       currentCommitProfilingMetadata = {
@@ -2259,8 +2240,11 @@ export function attach(
         maxActualDuration: 0,
         priorityLevel:
           priorityLevel == null ? null : formatPriorityLevel(priorityLevel),
-        effectDuration,
-        passiveEffectDuration,
+
+        // Initialize to null; if new enough React version is running,
+        // these values will be read during separate handlePostCommitFiberRoot() call.
+        effectDuration: null,
+        passiveEffectDuration: null,
       };
     }
 
@@ -3856,6 +3840,7 @@ export function attach(
     getProfilingData,
     handleCommitFiberRoot,
     handleCommitFiberUnmount,
+    handlePostCommitFiberRoot,
     inspectElement,
     logElementToConsole,
     prepareViewAttributeSource,
diff --git a/packages/react-devtools-shared/src/backend/types.js b/packages/react-devtools-shared/src/backend/types.js
index c0ef91021f073..ea83d77666175 100644
--- a/packages/react-devtools-shared/src/backend/types.js
+++ b/packages/react-devtools-shared/src/backend/types.js
@@ -326,6 +326,7 @@ export type RendererInterface = {
   getPathForElement: (id: number) => Array<PathFrame> | null,
   handleCommitFiberRoot: (fiber: Object, commitPriority?: number) => void,
   handleCommitFiberUnmount: (fiber: Object) => void,
+  handlePostCommitFiberRoot: (fiber: Object) => void,
   inspectElement: (
     requestID: number,
     id: number,
diff --git a/packages/react-devtools-shared/src/backend/utils.js b/packages/react-devtools-shared/src/backend/utils.js
index 593459d78f646..22f70e32e7d02 100644
--- a/packages/react-devtools-shared/src/backend/utils.js
+++ b/packages/react-devtools-shared/src/backend/utils.js
@@ -118,6 +118,26 @@ export function copyWithSet(
   return updated;
 }
 
+export function getEffectDurations(root: Object) {
+  // Profiling durations are only available for certain builds.
+  // If available, they'll be stored on the HostRoot.
+  let effectDuration = null;
+  let passiveEffectDuration = null;
+  const hostRoot = root.current;
+  if (hostRoot != null) {
+    const stateNode = hostRoot.stateNode;
+    if (stateNode != null) {
+      effectDuration =
+        stateNode.effectDuration != null ? stateNode.effectDuration : null;
+      passiveEffectDuration =
+        stateNode.passiveEffectDuration != null
+          ? stateNode.passiveEffectDuration
+          : null;
+    }
+  }
+  return {effectDuration, passiveEffectDuration};
+}
+
 export function serializeToString(data: any): string {
   const cache = new Set();
   // Use a custom replacer function to protect against circular references.
diff --git a/packages/react-devtools-shared/src/hook.js b/packages/react-devtools-shared/src/hook.js
index e29ad7abe956d..a4724f6f6b92b 100644
--- a/packages/react-devtools-shared/src/hook.js
+++ b/packages/react-devtools-shared/src/hook.js
@@ -287,6 +287,13 @@ export function installHook(target: any): DevToolsHook | null {
     }
   }
 
+  function onPostCommitFiberRoot(rendererID, root) {
+    const rendererInterface = rendererInterfaces.get(rendererID);
+    if (rendererInterface != null) {
+      rendererInterface.handlePostCommitFiberRoot(root);
+    }
+  }
+
   // TODO: More meaningful names for "rendererInterfaces" and "renderers".
   const fiberRoots = {};
   const rendererInterfaces = new Map();
@@ -315,6 +322,7 @@ export function installHook(target: any): DevToolsHook | null {
     checkDCE,
     onCommitFiberUnmount,
     onCommitFiberRoot,
+    onPostCommitFiberRoot,
   };
 
   Object.defineProperty(
diff --git a/packages/react-devtools-shell/src/app/InteractionTracing/index.js b/packages/react-devtools-shell/src/app/InteractionTracing/index.js
index 544b335d0b36a..aab8e77e90910 100644
--- a/packages/react-devtools-shell/src/app/InteractionTracing/index.js
+++ b/packages/react-devtools-shell/src/app/InteractionTracing/index.js
@@ -21,6 +21,14 @@ import {
   unstable_wrap as wrap,
 } from 'scheduler/tracing';
 
+function sleep(ms) {
+  const start = performance.now();
+  let now;
+  do {
+    now = performance.now();
+  } while (now - ms < start);
+}
+
 export default function InteractionTracing() {
   const [count, setCount] = useState(0);
   const [shouldCascade, setShouldCascade] = useState(false);
@@ -75,7 +83,11 @@ export default function InteractionTracing() {
   }, [count, shouldCascade]);
 
   useLayoutEffect(() => {
-    Math.sqrt(100 * 100 * 100 * 100 * 100);
+    sleep(150);
+  });
+
+  useEffect(() => {
+    sleep(300);
   });
 
   return (
diff --git a/packages/react-reconciler/src/ReactFiberDevToolsHook.new.js b/packages/react-reconciler/src/ReactFiberDevToolsHook.new.js
index a98e569b095b9..e7bde59e20cba 100644
--- a/packages/react-reconciler/src/ReactFiberDevToolsHook.new.js
+++ b/packages/react-reconciler/src/ReactFiberDevToolsHook.new.js
@@ -134,6 +134,24 @@ export function onCommitRoot(root: FiberRoot, eventPriority: EventPriority) {
   }
 }
 
+export function onPostCommitRoot(root: FiberRoot) {
+  if (
+    injectedHook &&
+    typeof injectedHook.onPostCommitFiberRoot === 'function'
+  ) {
+    try {
+      injectedHook.onPostCommitFiberRoot(rendererID, root);
+    } catch (err) {
+      if (__DEV__) {
+        if (!hasLoggedError) {
+          hasLoggedError = true;
+          console.error('React instrumentation encountered an error: %s', err);
+        }
+      }
+    }
+  }
+}
+
 export function onCommitUnmount(fiber: Fiber) {
   if (injectedHook && typeof injectedHook.onCommitFiberUnmount === 'function') {
     try {
diff --git a/packages/react-reconciler/src/ReactFiberDevToolsHook.old.js b/packages/react-reconciler/src/ReactFiberDevToolsHook.old.js
index 43b9f360faa3a..494138685e104 100644
--- a/packages/react-reconciler/src/ReactFiberDevToolsHook.old.js
+++ b/packages/react-reconciler/src/ReactFiberDevToolsHook.old.js
@@ -134,6 +134,24 @@ export function onCommitRoot(root: FiberRoot, eventPriority: EventPriority) {
   }
 }
 
+export function onPostCommitRoot(root: FiberRoot) {
+  if (
+    injectedHook &&
+    typeof injectedHook.onPostCommitFiberRoot === 'function'
+  ) {
+    try {
+      injectedHook.onPostCommitFiberRoot(rendererID, root);
+    } catch (err) {
+      if (__DEV__) {
+        if (!hasLoggedError) {
+          hasLoggedError = true;
+          console.error('React instrumentation encountered an error: %s', err);
+        }
+      }
+    }
+  }
+}
+
 export function onCommitUnmount(fiber: Fiber) {
   if (injectedHook && typeof injectedHook.onCommitFiberUnmount === 'function') {
     try {
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
index 425c46851aaba..3344361075e66 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.new.js
@@ -229,7 +229,10 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
-import {onCommitRoot as onCommitRootDevTools} from './ReactFiberDevToolsHook.new';
+import {
+  onCommitRoot as onCommitRootDevTools,
+  onPostCommitRoot as onPostCommitRootDevTools,
+} from './ReactFiberDevToolsHook.new';
 import {onCommitRoot as onCommitRootTestSelector} from './ReactTestSelectors';
 
 // Used by `act`
@@ -2156,6 +2159,14 @@ function flushPassiveEffectsImpl() {
   nestedPassiveUpdateCount =
     rootWithPendingPassiveEffects === null ? 0 : nestedPassiveUpdateCount + 1;
 
+  // TODO: Move to commitPassiveMountEffects
+  onPostCommitRootDevTools(root);
+  if (enableProfilerTimer && enableProfilerCommitHooks) {
+    const stateNode = root.current.stateNode;
+    stateNode.effectDuration = 0;
+    stateNode.passiveEffectDuration = 0;
+  }
+
   return true;
 }
 
diff --git a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
index b22901ff84ec3..73230f5787772 100644
--- a/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
+++ b/packages/react-reconciler/src/ReactFiberWorkLoop.old.js
@@ -229,7 +229,10 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
-import {onCommitRoot as onCommitRootDevTools} from './ReactFiberDevToolsHook.old';
+import {
+  onCommitRoot as onCommitRootDevTools,
+  onPostCommitRoot as onPostCommitRootDevTools,
+} from './ReactFiberDevToolsHook.old';
 import {onCommitRoot as onCommitRootTestSelector} from './ReactTestSelectors';
 
 // Used by `act`
@@ -2156,6 +2159,14 @@ function flushPassiveEffectsImpl() {
   nestedPassiveUpdateCount =
     rootWithPendingPassiveEffects === null ? 0 : nestedPassiveUpdateCount + 1;
 
+  // TODO: Move to commitPassiveMountEffects
+  onPostCommitRootDevTools(root);
+  if (enableProfilerTimer && enableProfilerCommitHooks) {
+    const stateNode = root.current.stateNode;
+    stateNode.effectDuration = 0;
+    stateNode.passiveEffectDuration = 0;
+  }
+
   return true;
 }