diff --git a/packages/react-reconciler/src/ReactDebugFiberPerf.js b/packages/react-reconciler/src/ReactDebugFiberPerf.js
index b5a3eee8bc15d..39e7bf44a7bf9 100644
--- a/packages/react-reconciler/src/ReactDebugFiberPerf.js
+++ b/packages/react-reconciler/src/ReactDebugFiberPerf.js
@@ -248,13 +248,18 @@ export function startRequestCallbackTimer(): void {
   }
 }
 
-export function stopRequestCallbackTimer(didExpire: boolean): void {
+export function stopRequestCallbackTimer(
+  didExpire: boolean,
+  expirationTime: number,
+): void {
   if (enableUserTimingAPI) {
     if (supportsUserTiming) {
       isWaitingForCallback = false;
       const warning = didExpire ? 'React was blocked by main thread' : null;
       endMark(
-        '(Waiting for async callback...)',
+        `(Waiting for async callback... will force flush in ${
+          expirationTime
+        } ms)`,
         '(Waiting for async callback...)',
         warning,
       );
diff --git a/packages/react-reconciler/src/ReactFiberScheduler.js b/packages/react-reconciler/src/ReactFiberScheduler.js
index af46e9bccbf2e..7b739bfd7c20f 100644
--- a/packages/react-reconciler/src/ReactFiberScheduler.js
+++ b/packages/react-reconciler/src/ReactFiberScheduler.js
@@ -1432,7 +1432,8 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
 
     if (enableUserTimingAPI && deadline !== null) {
       const didExpire = nextFlushedExpirationTime < recalculateCurrentTime();
-      stopRequestCallbackTimer(didExpire);
+      const timeout = expirationTimeToMs(nextFlushedExpirationTime);
+      stopRequestCallbackTimer(didExpire, timeout);
     }
 
     if (isAsync) {
diff --git a/packages/react-reconciler/src/__tests__/__snapshots__/ReactIncrementalPerf-test.internal.js.snap b/packages/react-reconciler/src/__tests__/__snapshots__/ReactIncrementalPerf-test.internal.js.snap
index c39fd8d513bb9..d6cf71c85f767 100644
--- a/packages/react-reconciler/src/__tests__/__snapshots__/ReactIncrementalPerf-test.internal.js.snap
+++ b/packages/react-reconciler/src/__tests__/__snapshots__/ReactIncrementalPerf-test.internal.js.snap
@@ -1,7 +1,7 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`ReactDebugFiberPerf captures all lifecycles 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Mount
 ⚛ (React Tree Reconciliation)
@@ -15,7 +15,7 @@ exports[`ReactDebugFiberPerf captures all lifecycles 1`] = `
   ⚛ (Calling Lifecycle Methods: 1 Total)
     ⚛ AllLifecycles.componentDidMount
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Update
 ⚛ (React Tree Reconciliation)
@@ -31,7 +31,7 @@ exports[`ReactDebugFiberPerf captures all lifecycles 1`] = `
   ⚛ (Calling Lifecycle Methods: 2 Total)
     ⚛ AllLifecycles.componentDidUpdate
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Unmount
 ⚛ (React Tree Reconciliation)
@@ -45,7 +45,7 @@ exports[`ReactDebugFiberPerf captures all lifecycles 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf deduplicates lifecycle names during commit to reduce overhead 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // The commit phase should mention A and B just once
 ⚛ (React Tree Reconciliation)
@@ -62,7 +62,7 @@ exports[`ReactDebugFiberPerf deduplicates lifecycle names during commit to reduc
     ⚛ A.componentDidUpdate
     ⚛ B.componentDidUpdate
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Because of deduplication, we don't know B was cascading,
 // but we should still see the warning for the commit phase.
@@ -112,7 +112,7 @@ exports[`ReactDebugFiberPerf does not schedule an extra callback if setState is
 `;
 
 exports[`ReactDebugFiberPerf does not treat setState from cWM or cWRP as cascading 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Should not print a warning
 ⚛ (React Tree Reconciliation)
@@ -125,7 +125,7 @@ exports[`ReactDebugFiberPerf does not treat setState from cWM or cWRP as cascadi
   ⚛ (Committing Host Effects: 1 Total)
   ⚛ (Calling Lifecycle Methods: 0 Total)
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Should not print a warning
 ⚛ (React Tree Reconciliation)
@@ -141,7 +141,7 @@ exports[`ReactDebugFiberPerf does not treat setState from cWM or cWRP as cascadi
 `;
 
 exports[`ReactDebugFiberPerf measures a simple reconciliation 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Mount
 ⚛ (React Tree Reconciliation)
@@ -153,7 +153,7 @@ exports[`ReactDebugFiberPerf measures a simple reconciliation 1`] = `
   ⚛ (Committing Host Effects: 1 Total)
   ⚛ (Calling Lifecycle Methods: 0 Total)
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Update
 ⚛ (React Tree Reconciliation)
@@ -165,7 +165,7 @@ exports[`ReactDebugFiberPerf measures a simple reconciliation 1`] = `
   ⚛ (Committing Host Effects: 2 Total)
   ⚛ (Calling Lifecycle Methods: 2 Total)
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Unmount
 ⚛ (React Tree Reconciliation)
@@ -178,7 +178,7 @@ exports[`ReactDebugFiberPerf measures a simple reconciliation 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf measures deferred work in chunks 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Start mounting Parent and A
 ⚛ (React Tree Reconciliation)
@@ -186,14 +186,14 @@ exports[`ReactDebugFiberPerf measures deferred work in chunks 1`] = `
     ⚛ A [mount]
       ⚛ Child [mount]
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Mount B just a little (but not enough to memoize)
 ⚛ (React Tree Reconciliation)
   ⚛ Parent [mount]
     ⚛ B [mount]
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Complete B and Parent
 ⚛ (React Tree Reconciliation)
@@ -218,7 +218,7 @@ exports[`ReactDebugFiberPerf measures deprioritized work 1`] = `
   ⚛ (Committing Host Effects: 1 Total)
   ⚛ (Calling Lifecycle Methods: 0 Total)
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 10737418210 ms)
 
 // Flush the child
 ⚛ (React Tree Reconciliation)
@@ -232,7 +232,7 @@ exports[`ReactDebugFiberPerf measures deprioritized work 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf recovers from caught errors 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Stop on Baddie and restart from Boundary
 ⚛ (React Tree Reconciliation)
@@ -262,7 +262,7 @@ exports[`ReactDebugFiberPerf recovers from caught errors 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf recovers from fatal errors 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Will fatal
 ⚛ (React Tree Reconciliation)
@@ -276,7 +276,7 @@ exports[`ReactDebugFiberPerf recovers from fatal errors 1`] = `
   ⚛ (Committing Host Effects: 1 Total)
   ⚛ (Calling Lifecycle Methods: 0 Total)
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Will reconcile from a clean state
 ⚛ (React Tree Reconciliation)
@@ -291,7 +291,7 @@ exports[`ReactDebugFiberPerf recovers from fatal errors 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf skips parents during setState 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Should include just A and B, no Parents
 ⚛ (React Tree Reconciliation)
@@ -306,7 +306,7 @@ exports[`ReactDebugFiberPerf skips parents during setState 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf supports portals 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 ⚛ (React Tree Reconciliation)
   ⚛ Parent [mount]
@@ -320,7 +320,7 @@ exports[`ReactDebugFiberPerf supports portals 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf supports returns 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 ⚛ (React Tree Reconciliation)
   ⚛ App [mount]
@@ -339,12 +339,12 @@ exports[`ReactDebugFiberPerf supports returns 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf warns if an in-progress update is interrupted 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 ⚛ (React Tree Reconciliation)
   ⚛ Foo [mount]
 
-⚛ (Waiting for async callback...)
+⚛ (Waiting for async callback... will force flush in 5230 ms)
   ⛔ (React Tree Reconciliation) Warning: A top-level update interrupted the previous render
     ⚛ Foo [mount]
   ⚛ (Committing Changes)
@@ -362,7 +362,7 @@ exports[`ReactDebugFiberPerf warns if an in-progress update is interrupted 1`] =
 `;
 
 exports[`ReactDebugFiberPerf warns if async work expires (starvation) 1`] = `
-"⛔ (Waiting for async callback...) Warning: React was blocked by main thread
+"⛔ (Waiting for async callback... will force flush in 5230 ms) Warning: React was blocked by main thread
 
 ⚛ (React Tree Reconciliation)
   ⚛ Foo [mount]
@@ -375,7 +375,7 @@ exports[`ReactDebugFiberPerf warns if async work expires (starvation) 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf warns on cascading renders from setState 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Should print a warning
 ⚛ (React Tree Reconciliation)
@@ -399,7 +399,7 @@ exports[`ReactDebugFiberPerf warns on cascading renders from setState 1`] = `
 `;
 
 exports[`ReactDebugFiberPerf warns on cascading renders from top-level render 1`] = `
-"⚛ (Waiting for async callback...)
+"⚛ (Waiting for async callback... will force flush in 5230 ms)
 
 // Rendering the first root
 ⚛ (React Tree Reconciliation)