diff --git a/tsdb/db.go b/tsdb/db.go
index 7a165e431..616213b03 100644
--- a/tsdb/db.go
+++ b/tsdb/db.go
@@ -1002,7 +1002,7 @@ func (a dbAppender) GetRef(lset labels.Labels, hash uint64) (storage.SeriesRef,
 	if g, ok := a.Appender.(storage.GetRef); ok {
 		return g.GetRef(lset, hash)
 	}
-	return 0, nil
+	return 0, labels.EmptyLabels()
 }
 
 func (a dbAppender) Commit() error {
diff --git a/tsdb/exemplar.go b/tsdb/exemplar.go
index 3718d9591..5ba3567e4 100644
--- a/tsdb/exemplar.go
+++ b/tsdb/exemplar.go
@@ -226,13 +226,16 @@ func (ce *CircularExemplarStorage) validateExemplar(key []byte, e exemplar.Exemp
 	// Exemplar label length does not include chars involved in text rendering such as quotes
 	// equals sign, or commas. See definition of const ExemplarMaxLabelLength.
 	labelSetLen := 0
-	for _, l := range e.Labels {
+	if err := e.Labels.Validate(func(l labels.Label) error {
 		labelSetLen += utf8.RuneCountInString(l.Name)
 		labelSetLen += utf8.RuneCountInString(l.Value)
 
 		if labelSetLen > exemplar.ExemplarMaxLabelSetLength {
 			return storage.ErrExemplarLabelLength
 		}
+		return nil
+	}); err != nil {
+		return err
 	}
 
 	idx, ok := ce.index[string(key)]
diff --git a/tsdb/head_append.go b/tsdb/head_append.go
index d5003188d..822863276 100644
--- a/tsdb/head_append.go
+++ b/tsdb/head_append.go
@@ -102,7 +102,7 @@ func (a *initAppender) GetRef(lset labels.Labels, hash uint64) (storage.SeriesRe
 	if g, ok := a.app.(storage.GetRef); ok {
 		return g.GetRef(lset, hash)
 	}
-	return 0, nil
+	return 0, labels.EmptyLabels()
 }
 
 func (a *initAppender) Commit() error {
@@ -312,7 +312,7 @@ func (a *headAppender) Append(ref storage.SeriesRef, lset labels.Labels, t int64
 	if s == nil {
 		// Ensure no empty labels have gotten through.
 		lset = lset.WithoutEmpty()
-		if len(lset) == 0 {
+		if lset.IsEmpty() {
 			return 0, errors.Wrap(ErrInvalidSample, "empty labelset")
 		}
 
@@ -494,7 +494,7 @@ func (a *headAppender) AppendHistogram(ref storage.SeriesRef, lset labels.Labels
 	if s == nil {
 		// Ensure no empty labels have gotten through.
 		lset = lset.WithoutEmpty()
-		if len(lset) == 0 {
+		if lset.IsEmpty() {
 			return 0, errors.Wrap(ErrInvalidSample, "empty labelset")
 		}
 
@@ -650,7 +650,7 @@ var _ storage.GetRef = &headAppender{}
 func (a *headAppender) GetRef(lset labels.Labels, hash uint64) (storage.SeriesRef, labels.Labels) {
 	s := a.head.series.getByHash(hash, lset)
 	if s == nil {
-		return 0, nil
+		return 0, labels.EmptyLabels()
 	}
 	// returned labels must be suitable to pass to Append()
 	return storage.SeriesRef(s.ref), s.lset
diff --git a/tsdb/head_read.go b/tsdb/head_read.go
index c6017e7b8..0a6aef2bd 100644
--- a/tsdb/head_read.go
+++ b/tsdb/head_read.go
@@ -155,7 +155,7 @@ func (h *headIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchB
 		h.head.metrics.seriesNotFound.Inc()
 		return storage.ErrNotFound
 	}
-	*lbls = append((*lbls)[:0], s.lset...)
+	lbls.CopyFrom(s.lset)
 
 	s.Lock()
 	defer s.Unlock()
@@ -222,9 +222,9 @@ func (h *headIndexReader) LabelNamesFor(ids ...storage.SeriesRef) ([]string, err
 		if memSeries == nil {
 			return nil, storage.ErrNotFound
 		}
-		for _, lbl := range memSeries.lset {
+		memSeries.lset.Range(func(lbl labels.Label) {
 			namesMap[lbl.Name] = struct{}{}
-		}
+		})
 	}
 	names := make([]string, 0, len(namesMap))
 	for name := range namesMap {
diff --git a/tsdb/ooo_head_read.go b/tsdb/ooo_head_read.go
index f63607dc9..d0b09963d 100644
--- a/tsdb/ooo_head_read.go
+++ b/tsdb/ooo_head_read.go
@@ -47,7 +47,7 @@ func NewOOOHeadIndexReader(head *Head, mint, maxt int64) *OOOHeadIndexReader {
 	return &OOOHeadIndexReader{hr}
 }
 
-func (oh *OOOHeadIndexReader) Series(ref storage.SeriesRef, lbls *labels.Labels, chks *[]chunks.Meta) error {
+func (oh *OOOHeadIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchBuilder, lbls *labels.Labels, chks *[]chunks.Meta) error {
 	return oh.series(ref, lbls, chks, 0)
 }
 
@@ -61,7 +61,7 @@ func (oh *OOOHeadIndexReader) series(ref storage.SeriesRef, lbls *labels.Labels,
 		oh.head.metrics.seriesNotFound.Inc()
 		return storage.ErrNotFound
 	}
-	*lbls = append((*lbls)[:0], s.lset...)
+	lbls.CopyFrom(s.lset)
 
 	if chks == nil {
 		return nil
@@ -400,7 +400,7 @@ func (ir *OOOCompactionHeadIndexReader) SortedPostings(p index.Postings) index.P
 	return p
 }
 
-func (ir *OOOCompactionHeadIndexReader) Series(ref storage.SeriesRef, lset *labels.Labels, chks *[]chunks.Meta) error {
+func (ir *OOOCompactionHeadIndexReader) Series(ref storage.SeriesRef, builder *labels.ScratchBuilder, lset *labels.Labels, chks *[]chunks.Meta) error {
 	return ir.ch.oooIR.series(ref, lset, chks, ir.ch.lastMmapRef)
 }
 
diff --git a/tsdb/querier.go b/tsdb/querier.go
index 4082279ae..34917dad0 100644
--- a/tsdb/querier.go
+++ b/tsdb/querier.go
@@ -529,8 +529,7 @@ func (b *blockBaseSeriesSet) Next() bool {
 			intervals = intervals.Add(tombstones.Interval{Mint: b.maxt + 1, Maxt: math.MaxInt64})
 		}
 
-		b.curr.labels = make(labels.Labels, len(b.bufLbls))
-		copy(b.curr.labels, b.bufLbls)
+		b.curr.labels = b.bufLbls.Copy()
 		b.curr.chks = chks
 		b.curr.intervals = intervals
 
@@ -866,7 +865,6 @@ func newBlockSeriesSet(i IndexReader, c ChunkReader, t tombstones.Reader, p inde
 			mint:            mint,
 			maxt:            maxt,
 			disableTrimming: disableTrimming,
-			bufLbls:         make(labels.Labels, 0, 10),
 		},
 	}
 }
@@ -898,7 +896,6 @@ func newBlockChunkSeriesSet(id ulid.ULID, i IndexReader, c ChunkReader, t tombst
 			mint:            mint,
 			maxt:            maxt,
 			disableTrimming: disableTrimming,
-			bufLbls:         make(labels.Labels, 0, 10),
 		},
 	}
 }