diff --git a/src/cmd/pprof/internal/profile/proto.go b/src/cmd/pprof/internal/profile/proto.go
index 475cf564fb4..11d7f9ff9b3 100644
--- a/src/cmd/pprof/internal/profile/proto.go
+++ b/src/cmd/pprof/internal/profile/proto.go
@@ -64,6 +64,20 @@ func encodeUint64(b *buffer, tag int, x uint64) {
 }
 
 func encodeUint64s(b *buffer, tag int, x []uint64) {
+	if len(x) > 2 {
+		// Use packed encoding
+		n1 := len(b.data)
+		for _, u := range x {
+			encodeVarint(b, u)
+		}
+		n2 := len(b.data)
+		encodeLength(b, tag, n2-n1)
+		n3 := len(b.data)
+		copy(b.tmp[:], b.data[n2:n3])
+		copy(b.data[n1+(n3-n2):], b.data[n1:n2])
+		copy(b.data[n1:], b.tmp[:n3-n2])
+		return
+	}
 	for _, u := range x {
 		encodeUint64(b, tag, u)
 	}
@@ -88,6 +102,26 @@ func encodeInt64Opt(b *buffer, tag int, x int64) {
 	encodeInt64(b, tag, x)
 }
 
+func encodeInt64s(b *buffer, tag int, x []int64) {
+	if len(x) > 2 {
+		// Use packed encoding
+		n1 := len(b.data)
+		for _, u := range x {
+			encodeVarint(b, uint64(u))
+		}
+		n2 := len(b.data)
+		encodeLength(b, tag, n2-n1)
+		n3 := len(b.data)
+		copy(b.tmp[:], b.data[n2:n3])
+		copy(b.data[n1+(n3-n2):], b.data[n1:n2])
+		copy(b.data[n1:], b.tmp[:n3-n2])
+		return
+	}
+	for _, u := range x {
+		encodeInt64(b, tag, u)
+	}
+}
+
 func encodeString(b *buffer, tag int, x string) {
 	encodeLength(b, tag, len(x))
 	b.data = append(b.data, x...)
@@ -243,6 +277,20 @@ func decodeInt64(b *buffer, x *int64) error {
 }
 
 func decodeInt64s(b *buffer, x *[]int64) error {
+	if b.typ == 2 {
+		// Packed encoding
+		data := b.data
+		for len(data) > 0 {
+			var u uint64
+			var err error
+
+			if u, data, err = decodeVarint(data); err != nil {
+				return err
+			}
+			*x = append(*x, int64(u))
+		}
+		return nil
+	}
 	var i int64
 	if err := decodeInt64(b, &i); err != nil {
 		return err
@@ -260,6 +308,20 @@ func decodeUint64(b *buffer, x *uint64) error {
 }
 
 func decodeUint64s(b *buffer, x *[]uint64) error {
+	if b.typ == 2 {
+		data := b.data
+		// Packed encoding
+		for len(data) > 0 {
+			var u uint64
+			var err error
+
+			if u, data, err = decodeVarint(data); err != nil {
+				return err
+			}
+			*x = append(*x, u)
+		}
+		return nil
+	}
 	var u uint64
 	if err := decodeUint64(b, &u); err != nil {
 		return err
diff --git a/src/cmd/pprof/internal/profile/proto_test.go b/src/cmd/pprof/internal/profile/proto_test.go
new file mode 100644
index 00000000000..c2613fc375a
--- /dev/null
+++ b/src/cmd/pprof/internal/profile/proto_test.go
@@ -0,0 +1,67 @@
+package profile
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestPackedEncoding(t *testing.T) {
+
+	type testcase struct {
+		uint64s []uint64
+		int64s  []int64
+		encoded []byte
+	}
+	for i, tc := range []testcase{
+		{
+			[]uint64{0, 1, 10, 100, 1000, 10000},
+			[]int64{1000, 0, 1000},
+			[]byte{10, 8, 0, 1, 10, 100, 232, 7, 144, 78, 18, 5, 232, 7, 0, 232, 7},
+		},
+		{
+			[]uint64{10000},
+			nil,
+			[]byte{8, 144, 78},
+		},
+		{
+			nil,
+			[]int64{-10000},
+			[]byte{16, 240, 177, 255, 255, 255, 255, 255, 255, 255, 1},
+		},
+	} {
+		source := &packedInts{tc.uint64s, tc.int64s}
+		if got, want := marshal(source), tc.encoded; !reflect.DeepEqual(got, want) {
+			t.Errorf("failed encode %d, got %v, want %v", i, got, want)
+		}
+
+		dest := new(packedInts)
+		if err := unmarshal(tc.encoded, dest); err != nil {
+			t.Errorf("failed decode %d: %v", i, err)
+			continue
+		}
+		if got, want := dest.uint64s, tc.uint64s; !reflect.DeepEqual(got, want) {
+			t.Errorf("failed decode uint64s %d, got %v, want %v", i, got, want)
+		}
+		if got, want := dest.int64s, tc.int64s; !reflect.DeepEqual(got, want) {
+			t.Errorf("failed decode int64s %d, got %v, want %v", i, got, want)
+		}
+	}
+}
+
+type packedInts struct {
+	uint64s []uint64
+	int64s  []int64
+}
+
+func (u *packedInts) decoder() []decoder {
+	return []decoder{
+		nil,
+		func(b *buffer, m message) error { return decodeUint64s(b, &m.(*packedInts).uint64s) },
+		func(b *buffer, m message) error { return decodeInt64s(b, &m.(*packedInts).int64s) },
+	}
+}
+
+func (u *packedInts) encode(b *buffer) {
+	encodeUint64s(b, 1, u.uint64s)
+	encodeInt64s(b, 2, u.int64s)
+}