2 files changed, 11 insertions, 1 deletions
diff --git a/src/testing/benchmark.go b/src/testing/benchmark.go
index 8b84444f38..2660c9bba0 100644
--- a/src/testing/benchmark.go
+++ b/src/testing/benchmark.go
@@ -366,6 +366,8 @@ func (b *B) ReportMetric(n float64, unit string) {
 func (b *B) stopOrScaleBLoop() bool {
 	timeElapsed := highPrecisionTimeSince(b.start)
 	if timeElapsed >= b.benchTime.d {
+		// Stop the timer so we don't count cleanup time
+		b.StopTimer()
 		return false
 	}
 	// Loop scaling
@@ -393,6 +395,7 @@ func (b *B) loopSlowPath() bool {
 			b.loopN++
 			return true
 		}
+		b.StopTimer()
 		return false
 	}
 	// Handles fixed time case
@@ -413,7 +416,8 @@ func (b *B) loopSlowPath() bool {
 //
 // Loop resets the benchmark timer the first time it is called in a benchmark,
 // so any setup performed prior to starting the benchmark loop does not count
-// toward the benchmark measurement.
+// toward the benchmark measurement. Likewise, when it returns false, it stops
+// the timer so cleanup code is not measured.
 //
 // The compiler never optimizes away calls to functions within the body of a
 // "for b.Loop() { ... }" loop. This prevents surprises that can otherwise occur
diff --git a/src/testing/loop_test.go b/src/testing/loop_test.go
index ae1a5e019b..7a1a93fcee 100644
--- a/src/testing/loop_test.go
+++ b/src/testing/loop_test.go
@@ -8,6 +8,7 @@ func TestBenchmarkBLoop(t *T) {
 	var initialStart highPrecisionTime
 	var firstStart highPrecisionTime
 	var lastStart highPrecisionTime
+	var runningEnd bool
 	runs := 0
 	iters := 0
 	finalBN := 0
@@ -22,6 +23,7 @@ func TestBenchmarkBLoop(t *T) {
 			iters++
 		}
 		finalBN = b.N
+		runningEnd = b.timerOn
 	})
 	// Verify that a b.Loop benchmark is invoked just once.
 	if runs != 1 {
@@ -46,6 +48,10 @@ func TestBenchmarkBLoop(t *T) {
 	if lastStart != firstStart {
 		t.Errorf("timer was reset during iteration")
 	}
+	// Verify that it stopped the timer after the last loop.
+	if runningEnd {
+		t.Errorf("timer was still running after last iteration")
+	}
 }
 
 // See also TestBenchmarkBLoop* in other files.