diff --git a/src/cmd/gc/order.c b/src/cmd/gc/order.c
index 2cd155d4d7..6603efe8d1 100644
--- a/src/cmd/gc/order.c
+++ b/src/cmd/gc/order.c
@@ -1031,6 +1031,18 @@ orderexpr(Node **np, Order *order)
 		}
 		break;
 
+	case OCMPSTR:
+		orderexpr(&n->left, order);
+		orderexpr(&n->right, order);
+		// Mark string(byteSlice) arguments to reuse byteSlice backing
+		// buffer during conversion. String comparison does not
+		// memorize the strings for later use, so it is safe.
+		if(n->left->op == OARRAYBYTESTR)
+			n->left->op = OARRAYBYTESTRTMP;
+		if(n->right->op == OARRAYBYTESTR)
+			n->right->op = OARRAYBYTESTRTMP;
+		break;
+
 	case OINDEXMAP:
 		// key must be addressable
 		orderexpr(&n->left, order);
diff --git a/src/runtime/string.go b/src/runtime/string.go
index 8aa0dd076d..6f7de4de1e 100644
--- a/src/runtime/string.go
+++ b/src/runtime/string.go
@@ -76,6 +76,7 @@ func slicebytetostringtmp(b []byte) string {
 	// First such case is a m[string(k)] lookup where
 	// m is a string-keyed map and k is a []byte.
 	// Second such case is "<"+string(b)+">" concatenation where b is []byte.
+	// Third such case is string(b)=="foo" comparison where b is []byte.
 
 	if raceenabled && len(b) > 0 {
 		racereadrangepc(unsafe.Pointer(&b[0]),
diff --git a/src/runtime/string_test.go b/src/runtime/string_test.go
index 1551ecc82b..03c8948467 100644
--- a/src/runtime/string_test.go
+++ b/src/runtime/string_test.go
@@ -158,3 +158,20 @@ func TestGostringnocopy(t *testing.T) {
 		t.Errorf("want %d, got %d", max+9, newmax)
 	}
 }
+
+func TestCompareTempString(t *testing.T) {
+	s := "foo"
+	b := []byte(s)
+	n := testing.AllocsPerRun(1000, func() {
+		if string(b) != s {
+			t.Fatalf("strings are not equal: '%v' and '%v'", string(b), s)
+		}
+		if string(b) == s {
+		} else {
+			t.Fatalf("strings are not equal: '%v' and '%v'", string(b), s)
+		}
+	})
+	if n != 0 {
+		t.Fatalf("want 0 allocs, got %v", n)
+	}
+}