1 files changed, 9 insertions, 6 deletions

diff --git a/lisp/progmodes/cc-styles.el b/lisp/progmodes/cc-styles.el
index cbe89033b1c..4adb0ac3870 100644
--- a/lisp/progmodes/cc-styles.el
+++ b/lisp/progmodes/cc-styles.el
@@ -7,7 +7,7 @@
 ;;             1985 Richard M. Stallman
 ;; Maintainer: cc-mode-help@python.org
 ;; Created:    22-Apr-1997 (split from cc-mode.el)
-;; Version:    5.17
+;; Version:    5.18
 ;; Keywords:   c languages oop
 
 ;; This file is part of GNU Emacs.
@@ -571,11 +571,14 @@ offset for that syntactic element.  Optional ADD says to add SYMBOL to
   ;; style.  Only do this once!
   (or (assoc "cc-mode" c-style-alist)
       (let (copyfunc)
-        (setq copyfunc (lambda (tree)
-                         (if (consp tree)
-                             (cons (funcall copyfunc (car tree))
-                                   (funcall copyfunc (cdr tree)))
-                           tree)))
+        ;; use built-in copy-tree if its there.
+        (if (fboundp 'copy-tree)
+            (setq copyfunc (symbol-function 'copy-tree))
+          (setq copyfunc (lambda (tree)
+                            (if (consp tree)
+                                (cons (funcall copyfunc (car tree))
+                                      (funcall copyfunc (cdr tree)))
+                              tree))))
         (c-add-style "cc-mode"
                      (mapcar
                       (function