diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index aff19ef4664..50148e205d0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2005-08-15  Ian Lance Taylor  <ian@airs.com>
+
+	* tree.c (build_string): Mark tree CONSTANT and INVARIANT.
+
 2005-08-15  DJ Delorie  <dj@redhat.com>
 
 	* config/m32c/mov.md (movqi_op): Immediates can't be moved to
@@ -18,7 +22,6 @@
 
 	* configure, config.in: Regenerate.
 
-
 2005-08-15  David Edelsohn  <edelsohn@gnu.org>
 
 	* config/rs6000/rs6000.md (QHSI): New mode macro.
diff --git a/gcc/tree.c b/gcc/tree.c
index 849482d3845..4ee70bf586b 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1053,6 +1053,8 @@ build_string (int len, const char *str)
 
   memset (s, 0, sizeof (struct tree_common));
   TREE_SET_CODE (s, STRING_CST);
+  TREE_CONSTANT (s) = 1;
+  TREE_INVARIANT (s) = 1;
   TREE_STRING_LENGTH (s) = len;
   memcpy ((char *) TREE_STRING_POINTER (s), str, len);
   ((char *) TREE_STRING_POINTER (s))[len] = '\0';