diff --git a/lib/promrelabel/relabel.go b/lib/promrelabel/relabel.go
index e5433e032..6d55f3b64 100644
--- a/lib/promrelabel/relabel.go
+++ b/lib/promrelabel/relabel.go
@@ -172,7 +172,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 		bb := relabelBufPool.Get()
 		for _, gl := range prc.graphiteLabelRules {
 			bb.B = gl.grt.Expand(bb.B[:0], gm.a)
-			valueStr := string(bb.B)
+			valueStr := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 			labels = setLabelValue(labels, labelsOffset, gl.targetLabel, valueStr)
 		}
 		relabelBufPool.Put(bb)
@@ -185,7 +185,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 		if prc.hasLabelReferenceInReplacement {
 			// Fill {{labelName}} references in the replacement
 			bb.B = fillLabelReferences(bb.B[:0], replacement, labels[labelsOffset:])
-			replacement = string(bb.B)
+			replacement = bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 		}
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
 		if prc.RegexAnchored == defaultRegexForRelabelConfig && !prc.hasCaptureGroupInTargetLabel {
@@ -193,7 +193,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 				// Fast path for the rule that copies source label values to destination:
 				// - source_labels: [...]
 				//   target_label: foobar
-				valueStr := string(bb.B)
+				valueStr := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 				relabelBufPool.Put(bb)
 				return setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
 			}
@@ -236,7 +236,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 		// and store the result at `target_label`
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		sourceStr := string(bb.B)
+		sourceStr := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 		relabelBufPool.Put(bb)
 		valueStr := prc.replaceStringSubmatchesFast(sourceStr)
 		if valueStr != sourceStr {
@@ -350,7 +350,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 	case "uppercase":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		valueStr := string(bb.B)
+		valueStr := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 		relabelBufPool.Put(bb)
 		valueStr = strings.ToUpper(valueStr)
 		labels = setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
@@ -358,7 +358,7 @@ func (prc *parsedRelabelConfig) apply(labels []prompbmarshal.Label, labelsOffset
 	case "lowercase":
 		bb := relabelBufPool.Get()
 		bb.B = concatLabelValues(bb.B[:0], src, prc.SourceLabels, prc.Separator)
-		valueStr := string(bb.B)
+		valueStr := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 		relabelBufPool.Put(bb)
 		valueStr = strings.ToLower(valueStr)
 		labels = setLabelValue(labels, labelsOffset, prc.TargetLabel, valueStr)
@@ -384,7 +384,7 @@ func (prc *parsedRelabelConfig) replaceFullStringFast(s string) string {
 		return s
 	}
 	if !strings.HasPrefix(s, prefix) {
-		// Fast path - s doesn't match literl prefix from regex
+		// Fast path - s doesn't match literal prefix from regex
 		return s
 	}
 	if replacement == "$1" {
@@ -447,7 +447,7 @@ func (prc *parsedRelabelConfig) replaceStringSubmatchesSlow(s string) string {
 func (prc *parsedRelabelConfig) expandCaptureGroups(template, source string, match []int) string {
 	bb := relabelBufPool.Get()
 	bb.B = prc.RegexAnchored.ExpandString(bb.B[:0], template, source, match)
-	s := string(bb.B)
+	s := bytesutil.InternString(bytesutil.ToUnsafeString(bb.B))
 	relabelBufPool.Put(bb)
 	return s
 }