Index: link-template.php
===================================================================
--- link-template.php	(revision 15473)
+++ link-template.php	(working copy)
@@ -1342,6 +1342,10 @@
  * @param bool $previous Optional, default is true. Whether display link to previous post.
  */
 function adjacent_post_link($format, $link, $in_same_cat = false, $excluded_categories = '', $previous = true) {
+	$override = apply_filters( 'override_adjacent_post_link', '' );
+	if( !empty( $override ) ) {
+		return $override;
+	}
 	if ( $previous && is_attachment() )
 		$post = & get_post($GLOBALS['post']->post_parent);
 	else