1 files changed, 11 insertions, 4 deletions
diff --git a/libgo/go/net/http/header.go b/libgo/go/net/http/header.go
index b699e7ef8ff..1e1ed981ecc 100644
--- a/libgo/go/net/http/header.go
+++ b/libgo/go/net/http/header.go
@@ -78,12 +78,19 @@ func (h Header) write(w io.Writer, trace *httptrace.ClientTrace) error {
 	return h.writeSubset(w, nil, trace)
 }
 
-func (h Header) clone() Header {
+// Clone returns a copy of h.
+func (h Header) Clone() Header {
+	// Find total number of values.
+	nv := 0
+	for _, vv := range h {
+		nv += len(vv)
+	}
+	sv := make([]string, nv) // shared backing array for headers' values
 	h2 := make(Header, len(h))
 	for k, vv := range h {
-		vv2 := make([]string, len(vv))
-		copy(vv2, vv)
-		h2[k] = vv2
+		n := copy(sv, vv)
+		h2[k] = sv[:n:n]
+		sv = sv[n:]
 	}
 	return h2
 }