diff --git a/src/runtime/metrics.go b/src/runtime/metrics.go
index 2bff44c4668..75ad318b07b 100644
--- a/src/runtime/metrics.go
+++ b/src/runtime/metrics.go
@@ -165,6 +165,12 @@ func initMetrics() {
 				out.scalar = uint64(in.heapStats.tinyAllocCount)
 			},
 		},
+		"/gc/limiter/last-enabled:gc-cycle": {
+			compute: func(_ *statAggregate, out *metricValue) {
+				out.kind = metricKindUint64
+				out.scalar = uint64(gcCPULimiter.lastEnabledCycle.Load())
+			},
+		},
 		"/gc/pauses:seconds": {
 			compute: func(_ *statAggregate, out *metricValue) {
 				hist := out.float64HistOrInit(timeHistBuckets)
diff --git a/src/runtime/metrics/description.go b/src/runtime/metrics/description.go
index a33d9a2c35a..ee99d3938df 100644
--- a/src/runtime/metrics/description.go
+++ b/src/runtime/metrics/description.go
@@ -140,6 +140,15 @@ var allDesc = []Description{
 		Kind:       KindUint64,
 		Cumulative: true,
 	},
+	{
+		Name: "/gc/limiter/last-enabled:gc-cycle",
+		Description: "GC cycle the last time the GC CPU limiter was enabled. " +
+			"This metric is useful for diagnosing the root cause of an out-of-memory " +
+			"error, because the limiter trades memory for CPU time when the GC's CPU " +
+			"time gets too high. This is most likely to occur with use of SetMemoryLimit. " +
+			"The first GC cycle is cycle 1, so a value of 0 indicates that it was never enabled.",
+		Kind: KindUint64,
+	},
 	{
 		Name:        "/gc/pauses:seconds",
 		Description: "Distribution individual GC-related stop-the-world pause latencies.",
diff --git a/src/runtime/metrics/doc.go b/src/runtime/metrics/doc.go
index b4d99f72bb5..28c9f6abb5e 100644
--- a/src/runtime/metrics/doc.go
+++ b/src/runtime/metrics/doc.go
@@ -102,6 +102,13 @@ Below is the full list of supported metrics, ordered lexicographically.
 		only their block. Each block is already accounted for in
 		allocs-by-size and frees-by-size.
 
+	/gc/limiter/last-enabled:gc-cycle
+		GC cycle the last time the GC CPU limiter was enabled.
+		This metric is useful for diagnosing the root cause of an out-of-memory
+		error, because the limiter trades memory for CPU time when the GC's CPU
+		time gets too high. This is most likely to occur with use of SetMemoryLimit.
+		The first GC cycle is cycle 1, so a value of 0 indicates that it was never enabled.
+
 	/gc/pauses:seconds
 		Distribution individual GC-related stop-the-world pause latencies.
 
diff --git a/src/runtime/mgclimit.go b/src/runtime/mgclimit.go
index b930af3340e..cbe5500be61 100644
--- a/src/runtime/mgclimit.go
+++ b/src/runtime/mgclimit.go
@@ -40,8 +40,8 @@ type gcCPULimiterState struct {
 		// - fill <= capacity
 		fill, capacity uint64
 	}
-	// TODO(mknyszek): Export this as a runtime/metric to provide an estimate of
-	// how much GC work is being dropped on the floor.
+	// overflow is the cumulative amount of GC CPU time that we tried to fill the
+	// bucket with but exceeded its capacity.
 	overflow uint64
 
 	// gcEnabled is an internal copy of gcBlackenEnabled that determines
@@ -65,6 +65,9 @@ type gcCPULimiterState struct {
 	// Updated under lock, but may be read concurrently.
 	lastUpdate atomic.Int64
 
+	// lastEnabledCycle is the GC cycle that last had the limiter enabled.
+	lastEnabledCycle atomic.Uint32
+
 	// nprocs is an internal copy of gomaxprocs, used to determine total available
 	// CPU time.
 	//
@@ -203,6 +206,7 @@ func (l *gcCPULimiterState) accumulate(mutatorTime, gcTime int64) {
 		l.bucket.fill = l.bucket.capacity
 		if !enabled {
 			l.enabled.Store(true)
+			l.lastEnabledCycle.Store(memstats.numgc + 1)
 		}
 		return
 	}
@@ -254,6 +258,7 @@ func (l *gcCPULimiterState) resetCapacity(now int64, nprocs int32) {
 	if l.bucket.fill > l.bucket.capacity {
 		l.bucket.fill = l.bucket.capacity
 		l.enabled.Store(true)
+		l.lastEnabledCycle.Store(memstats.numgc + 1)
 	} else if l.bucket.fill < l.bucket.capacity {
 		l.enabled.Store(false)
 	}