diff --git a/CHANGELOG.md b/CHANGELOG.md
index e081131e63c..61159e50f13 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
 * [BUGFIX] Query Frontend: If 'LogQueriesLongerThan' is set to < 0, log all queries as described in the docs. #4633
 * [BUGFIX] Distributor: update defaultReplicationStrategy to not fail with extend-write when a single instance is unhealthy. #4636
 * [BUGFIX] Distributor: Fix race condition on `/series` introduced by #4683. #4716
+* [BUGFIX] Distributor: Fix a memory leak in distributor due to the cluster label. #4739
 
 ## 1.11.0 2021-11-25
 
diff --git a/pkg/distributor/ha_tracker.go b/pkg/distributor/ha_tracker.go
index 9bf38c800bd..dd0f74d9c55 100644
--- a/pkg/distributor/ha_tracker.go
+++ b/pkg/distributor/ha_tracker.go
@@ -471,7 +471,9 @@ func findHALabels(replicaLabel, clusterLabel string, labels []cortexpb.LabelAdap
 			replica = pair.Value
 		}
 		if pair.Name == clusterLabel {
-			cluster = pair.Value
+			// cluster label is unmarshalled into yoloString, which retains original remote write request body in memory.
+			// Hence, we clone the yoloString to allow the request body to be garbage collected.
+			cluster = util.StringsClone(pair.Value)
 		}
 	}
 
diff --git a/pkg/util/strings.go b/pkg/util/strings.go
index e4c93bc07a8..e7f7c3aceb4 100644
--- a/pkg/util/strings.go
+++ b/pkg/util/strings.go
@@ -1,5 +1,7 @@
 package util
 
+import "unsafe"
+
 // StringsContain returns true if the search value is within the list of input values.
 func StringsContain(values []string, search string) bool {
 	for _, v := range values {
@@ -19,3 +21,11 @@ func StringsMap(values []string) map[string]bool {
 	}
 	return out
 }
+
+// StringsClone returns a copy input s
+// see: https://github.com/golang/go/blob/master/src/strings/clone.go
+func StringsClone(s string) string {
+	b := make([]byte, len(s))
+	copy(b, s)
+	return *(*string)(unsafe.Pointer(&b))
+}