diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 992d2abb6a..955964c721 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -26,7 +26,7 @@ import (
 	"time"
 )
 
-func cpuHogger(f func(), dur time.Duration) {
+func cpuHogger(f func() int, dur time.Duration) {
 	// We only need to get one 100 Hz clock tick, so we've got
 	// a large safety buffer.
 	// But do at least 500 iterations (which should take about 100ms),
@@ -46,7 +46,7 @@ var (
 // The actual CPU hogging function.
 // Must not call other functions nor access heap/globals in the loop,
 // otherwise under race detector the samples will be in the race runtime.
-func cpuHog1() {
+func cpuHog1() int {
 	foo := salt1
 	for i := 0; i < 1e5; i++ {
 		if foo > 0 {
@@ -55,10 +55,10 @@ func cpuHog1() {
 			foo *= foo + 1
 		}
 	}
-	salt1 = foo
+	return foo
 }
 
-func cpuHog2() {
+func cpuHog2() int {
 	foo := salt2
 	for i := 0; i < 1e5; i++ {
 		if foo > 0 {
@@ -67,7 +67,7 @@ func cpuHog2() {
 			foo *= foo + 2
 		}
 	}
-	salt2 = foo
+	return foo
 }
 
 func TestCPUProfile(t *testing.T) {
@@ -95,8 +95,9 @@ func TestCPUProfileInlining(t *testing.T) {
 	})
 }
 
-func inlinedCaller() {
+func inlinedCaller() int {
 	inlinedCallee()
+	return 0
 }
 
 func inlinedCallee() {
@@ -716,6 +717,28 @@ func TestCPUProfileLabel(t *testing.T) {
 	})
 }
 
+func TestLabelRace(t *testing.T) {
+	// Test the race detector annotations for synchronization
+	// between settings labels and consuming them from the
+	// profile.
+	testCPUProfile(t, []string{"runtime/pprof.cpuHogger;key=value"}, func(dur time.Duration) {
+		start := time.Now()
+		var wg sync.WaitGroup
+		for time.Since(start) < dur {
+			for i := 0; i < 10; i++ {
+				wg.Add(1)
+				go func() {
+					Do(context.Background(), Labels("key", "value"), func(context.Context) {
+						cpuHogger(cpuHog1, time.Millisecond)
+					})
+					wg.Done()
+				}()
+			}
+			wg.Wait()
+		}
+	})
+}
+
 // Check that there is no deadlock when the program receives SIGPROF while in
 // 64bit atomics' critical section. Used to happen on mips{,le}. See #20146.
 func TestAtomicLoadStore64(t *testing.T) {
diff --git a/src/runtime/profbuf.go b/src/runtime/profbuf.go
index 2719238bc1..f40881aed5 100644
--- a/src/runtime/profbuf.go
+++ b/src/runtime/profbuf.go
@@ -545,7 +545,7 @@ Read:
 	b.rNext = br.addCountsAndClearFlags(skip+di, ti)
 
 	if raceenabled {
-		// Match racewritepc in runtime_setProfLabel,
+		// Match racereleasemerge in runtime_setProfLabel,
 		// so that the setting of the labels in runtime_setProfLabel
 		// is treated as happening before any use of the labels
 		// by our caller. The synchronization on labelSync itself is a fiction
diff --git a/src/runtime/proflabel.go b/src/runtime/proflabel.go
index 1b41a8a16e..b2a161729e 100644
--- a/src/runtime/proflabel.go
+++ b/src/runtime/proflabel.go
@@ -13,8 +13,23 @@ func runtime_setProfLabel(labels unsafe.Pointer) {
 	// Introduce race edge for read-back via profile.
 	// This would more properly use &getg().labels as the sync address,
 	// but we do the read in a signal handler and can't call the race runtime then.
+	//
+	// This uses racereleasemerge rather than just racerelease so
+	// the acquire in profBuf.read synchronizes with *all* prior
+	// setProfLabel operations, not just the most recent one. This
+	// is important because profBuf.read will observe different
+	// labels set by different setProfLabel operations on
+	// different goroutines, so it needs to synchronize with all
+	// of them (this wouldn't be an issue if we could synchronize
+	// on &getg().labels since we would synchronize with each
+	// most-recent labels write separately.)
+	//
+	// racereleasemerge is like a full read-modify-write on
+	// labelSync, rather than just a store-release, so it carries
+	// a dependency on the previous racereleasemerge, which
+	// ultimately carries forward to the acquire in profBuf.read.
 	if raceenabled {
-		racerelease(unsafe.Pointer(&labelSync))
+		racereleasemerge(unsafe.Pointer(&labelSync))
 	}
 	getg().labels = labels
 }