Index: wp-includes/user.php
===================================================================
--- wp-includes/user.php	(revision 40052)
+++ wp-includes/user.php	(working copy)
@@ -2335,7 +2335,14 @@
 	if ( $errors->get_error_code() )
 		return $errors;
 
-	$user_pass = wp_generate_password( 12, false );
+        /**
+	 * Filters the password length of a user being registered.
+	 *
+	 * @param int $pass_length the password length.
+	 */
+	$length = apply_filters( 'user_password_length', $length = 12 );
+
+	$user_pass = wp_generate_password( $length, false );
 	$user_id = wp_create_user( $sanitized_user_login, $user_pass, $user_email );
 	if ( ! $user_id || is_wp_error( $user_id ) ) {
 		$errors->add( 'registerfail', sprintf( __( '<strong>ERROR</strong>: Couldn&#8217;t register you&hellip; please contact the <a href="mailto:%s">webmaster</a> !' ), get_option( 'admin_email' ) ) );