--- common.inc	2009-01-17 04:26:09.000000000 +0900
+++ /www/d5.org/includes/common.inc	2009-04-03 16:29:40.000000000 +0900
@@ -1298,11 +1298,25 @@ function url($path = NULL, $query = NULL
     $clean_url = (bool)variable_get('clean_url', '0');
   }
 
-  $base = ($absolute ? $base_url . '/' : base_path());
+  // Preserve the original path before aliasing.
+  $original_path = $path;
 
   // The special path '<front>' links to the default front page.
-  if (!empty($path) && $path != '<front>') {
+  if ($path == '<front>') {
+    $path = '';
+  }
+  elseif (!empty($path)) {
     $path = drupal_get_path_alias($path);
+  }
+
+  if (function_exists('custom_url_rewrite_outbound')) {
+    // Modules may alter outbound links by reference.
+    custom_url_rewrite_outbound($path, $query, $fragment, $absolute, $base_url, $original_path);
+  }
+
+  $base = ($absolute ? $base_url . '/' : base_path());
+
+  if (!empty($path)) {
     $path = drupal_urlencode($path);
     if (!$clean_url) {
       if (isset($query)) {