diff --git a/packages/react-art/src/ReactARTHostConfig.js b/packages/react-art/src/ReactARTHostConfig.js
index cadf311d54ffd..6a02366979a07 100644
--- a/packages/react-art/src/ReactARTHostConfig.js
+++ b/packages/react-art/src/ReactARTHostConfig.js
@@ -471,3 +471,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: any): void {
   // noop
 }
+
+export function unmountNode(node: any): void {
+  // noop
+}
diff --git a/packages/react-dom/src/client/ReactDOMComponentTree.js b/packages/react-dom/src/client/ReactDOMComponentTree.js
index fbf0a81e29064..1c09f24931aee 100644
--- a/packages/react-dom/src/client/ReactDOMComponentTree.js
+++ b/packages/react-dom/src/client/ReactDOMComponentTree.js
@@ -43,6 +43,17 @@ const internalEventHandlersKey = '__reactEvents$' + randomKey;
 const internalEventHandlerListenersKey = '__reactListeners$' + randomKey;
 const internalEventHandlesSetKey = '__reactHandles$' + randomKey;
 
+export function unmountNode(
+  node: Instance | TextInstance | SuspenseInstance | ReactScopeInstance,
+): void {
+  delete (node: any)[internalInstanceKey];
+  delete (node: any)[internalPropsKey];
+  delete (node: any)[internalContainerInstanceKey];
+  delete (node: any)[internalEventHandlersKey];
+  delete (node: any)[internalEventHandlerListenersKey];
+  delete (node: any)[internalEventHandlesSetKey];
+}
+
 export function precacheFiberNode(
   hostInst: Fiber,
   node: Instance | TextInstance | SuspenseInstance | ReactScopeInstance,
diff --git a/packages/react-dom/src/client/ReactDOMHostConfig.js b/packages/react-dom/src/client/ReactDOMHostConfig.js
index dfd29b375a41b..301bd2e72ef8a 100644
--- a/packages/react-dom/src/client/ReactDOMHostConfig.js
+++ b/packages/react-dom/src/client/ReactDOMHostConfig.js
@@ -24,6 +24,7 @@ import {
   getFiberFromScopeInstance,
   getInstanceFromNode as getInstanceFromNodeDOMTree,
   isContainerMarkedAsRoot,
+  unmountNode as unmountNodeFromDOMTree,
 } from './ReactDOMComponentTree';
 import {hasRole} from './DOMAccessibilityRoles';
 import {
@@ -1209,3 +1210,7 @@ export function setupIntersectionObserver(
     },
   };
 }
+
+export function unmountNode(node: any): void {
+  unmountNodeFromDOMTree(node);
+}
diff --git a/packages/react-native-renderer/src/ReactFabricHostConfig.js b/packages/react-native-renderer/src/ReactFabricHostConfig.js
index 85eb2a741ffac..121480051a4a5 100644
--- a/packages/react-native-renderer/src/ReactFabricHostConfig.js
+++ b/packages/react-native-renderer/src/ReactFabricHostConfig.js
@@ -481,3 +481,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: Instance): void {
   // noop
 }
+
+export function unmountNode(node: any): void {
+  // noop
+}
diff --git a/packages/react-native-renderer/src/ReactNativeHostConfig.js b/packages/react-native-renderer/src/ReactNativeHostConfig.js
index d626a175d9340..f1ec3143020ed 100644
--- a/packages/react-native-renderer/src/ReactNativeHostConfig.js
+++ b/packages/react-native-renderer/src/ReactNativeHostConfig.js
@@ -538,3 +538,7 @@ export function afterActiveInstanceBlur() {
 export function preparePortalMount(portalInstance: Instance): void {
   // noop
 }
+
+export function unmountNode(node: any): void {
+  // noop
+}
diff --git a/packages/react-noop-renderer/src/createReactNoop.js b/packages/react-noop-renderer/src/createReactNoop.js
index 80c888a88e53d..428ece3318265 100644
--- a/packages/react-noop-renderer/src/createReactNoop.js
+++ b/packages/react-noop-renderer/src/createReactNoop.js
@@ -420,6 +420,9 @@ function createReactNoop(reconciler: Function, useMutation: boolean) {
     getInstanceFromScope() {
       throw new Error('Not yet implemented.');
     },
+
+    unmountNode() {
+    },
   };
 
   const hostConfig = useMutation
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.new.js b/packages/react-reconciler/src/ReactFiberCommitWork.new.js
index 7985366d3f67c..3ba14ef6569bb 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.new.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.new.js
@@ -35,6 +35,7 @@ import {
   enableSuspenseCallback,
   enableScopeAPI,
   enableStrictEffects,
+  enableStrongMemoryCleanup,
 } from 'shared/ReactFeatureFlags';
 import {
   FunctionComponent,
@@ -60,6 +61,9 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
+import {
+  unmountNode,
+} from './ReactFiberHostConfig';
 import {
   NoFlags,
   ContentReset,
@@ -1212,9 +1216,24 @@ function detachFiberMutation(fiber: Fiber) {
   fiber.return = null;
 }
 
-export function detachFiberAfterEffects(fiber: Fiber): void {
+export function detachFiberAfterEffects(
+  fiber: Fiber,
+  recurseIntoSibbling: ?boolean,
+): void {
   // Null out fields to improve GC for references that may be lingering (e.g. DevTools).
   // Note that we already cleared the return pointer in detachFiberMutation().
+  if (enableStrongMemoryCleanup) {
+    if (fiber.child) {
+      detachFiberAfterEffects(fiber.child, true);
+    }
+    if (fiber.sibling && recurseIntoSibbling === true) {
+      detachFiberAfterEffects(fiber.sibling, true);
+    }
+    if (fiber.stateNode) {
+      unmountNode(fiber.stateNode);
+    }
+    fiber.return = null;
+  }
   fiber.alternate = null;
   fiber.child = null;
   fiber.deletions = null;
diff --git a/packages/react-reconciler/src/ReactFiberCommitWork.old.js b/packages/react-reconciler/src/ReactFiberCommitWork.old.js
index d50095b3bebb1..e405d64abcc8f 100644
--- a/packages/react-reconciler/src/ReactFiberCommitWork.old.js
+++ b/packages/react-reconciler/src/ReactFiberCommitWork.old.js
@@ -35,6 +35,7 @@ import {
   enableSuspenseCallback,
   enableScopeAPI,
   enableStrictEffects,
+  enableStrongMemoryCleanup,
 } from 'shared/ReactFeatureFlags';
 import {
   FunctionComponent,
@@ -60,6 +61,9 @@ import {
   hasCaughtError,
   clearCaughtError,
 } from 'shared/ReactErrorUtils';
+import {
+  unmountNode,
+} from './ReactFiberHostConfig';
 import {
   NoFlags,
   ContentReset,
@@ -1212,9 +1216,24 @@ function detachFiberMutation(fiber: Fiber) {
   fiber.return = null;
 }
 
-export function detachFiberAfterEffects(fiber: Fiber): void {
+export function detachFiberAfterEffects(
+  fiber: Fiber,
+  recurseIntoSibbling: ?boolean,
+): void {
   // Null out fields to improve GC for references that may be lingering (e.g. DevTools).
   // Note that we already cleared the return pointer in detachFiberMutation().
+  if (enableStrongMemoryCleanup) {
+    if (fiber.child) {
+      detachFiberAfterEffects(fiber.child, true);
+    }
+    if (fiber.sibling && recurseIntoSibbling === true) {
+      detachFiberAfterEffects(fiber.sibling, true);
+    }
+    if (fiber.stateNode) {
+      unmountNode(fiber.stateNode);
+    }
+    fiber.return = null;
+  }
   fiber.alternate = null;
   fiber.child = null;
   fiber.deletions = null;
diff --git a/packages/react-test-renderer/src/ReactTestHostConfig.js b/packages/react-test-renderer/src/ReactTestHostConfig.js
index a787d31840af3..babb0c2437215 100644
--- a/packages/react-test-renderer/src/ReactTestHostConfig.js
+++ b/packages/react-test-renderer/src/ReactTestHostConfig.js
@@ -360,3 +360,7 @@ export function prepareScopeUpdate(scopeInstance: Object, inst: Object): void {
 export function getInstanceFromScope(scopeInstance: Object): null | Object {
   return nodeToInstanceMap.get(scopeInstance) || null;
 }
+
+export function unmountNode(node: any): void {
+  // noop
+}
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 75ab4b6842d90..2a3d0a337bf88 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -112,6 +112,9 @@ export const disableNativeComponentFrames = false;
 // If there are no still-mounted boundaries, the errors should be rethrown.
 export const skipUnmountedBoundaries = false;
 
+// When a node is unmounted, recurse into the Fiber subtree and clean out references.
+export const enableStrongMemoryCleanup = false;
+
 // --------------------------
 // Future APIs to be deprecated
 // --------------------------
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index b6a8016ec8b77..443c489c0063f 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -46,6 +46,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index cb8721af25fe9..bac13f5091b78 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index b504491d98de2..da03038c0211a 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
index ddab49284e437..eda47cde1139b 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.native.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
index 7098bfed2aa5b..9b02f6408229f 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.www.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.js b/packages/shared/forks/ReactFeatureFlags.testing.js
index a321f5ea12f92..7bb7ed424c7bd 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = false;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = false;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.testing.www.js b/packages/shared/forks/ReactFeatureFlags.testing.www.js
index bb6a952355657..8834238b02b14 100644
--- a/packages/shared/forks/ReactFeatureFlags.testing.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.testing.www.js
@@ -45,6 +45,7 @@ export const enableLegacyFBSupport = !__EXPERIMENTAL__;
 export const enableFilterEmptyStringAttributesDOM = false;
 export const disableNativeComponentFrames = false;
 export const skipUnmountedBoundaries = true;
+export const enableStrongMemoryCleanup = false;
 
 export const enableNewReconciler = false;
 export const deferRenderPhaseUpdateToNextBatch = true;
diff --git a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
index df98012634970..f58e0da1e80b9 100644
--- a/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
+++ b/packages/shared/forks/ReactFeatureFlags.www-dynamic.js
@@ -52,6 +52,7 @@ export const disableNativeComponentFrames = false;
 export const createRootStrictEffectsByDefault = false;
 export const enableStrictEffects = false;
 export const enableUseRefAccessWarning = __VARIANT__;
+export const enableStrongMemoryCleanup = __VARIANT__;
 
 export const enableProfilerNestedUpdateScheduledHook = __VARIANT__;
 export const disableSchedulerTimeoutInWorkLoop = __VARIANT__;
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 893c2699b0d07..25b88a019f1da 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -33,6 +33,7 @@ export const {
   disableSchedulerTimeoutInWorkLoop,
   enableSyncMicroTasks,
   enableLazyContextPropagation,
+  enableStrongMemoryCleanup,
 } = dynamicFeatureFlags;
 
 // On WWW, __EXPERIMENTAL__ is used for a new modern build.