diff --git a/classes/Session.php b/classes/Session.php
index e1c83ad4dc..166b89815a 100644
--- a/classes/Session.php
+++ b/classes/Session.php
@@ -156,6 +156,13 @@ class Session extends Memcached_DataObject
         $session->selectAdd();
         $session->selectAdd('id');
 
+        $limit = common_config('sessions', 'gc_limit');
+        if ($limit > 0) {
+            // On large sites, too many sessions to expire
+            // at once will just result in failure.
+            $session->limit($limit);
+        }
+
         $session->find();
 
         while ($session->fetch()) {
diff --git a/lib/default.php b/lib/default.php
index 85d27f5220..4b28e3238b 100644
--- a/lib/default.php
+++ b/lib/default.php
@@ -261,8 +261,9 @@ $default =
         'search' =>
         array('type' => 'fulltext'),
         'sessions' =>
-        array('handle' => false, // whether to handle sessions ourselves
-              'debug' => false), // debugging output for sessions
+        array('handle' => false,   // whether to handle sessions ourselves
+              'debug' => false,    // debugging output for sessions
+              'gc_limit' => 1000), // max sessions to expire at a time
         'design' =>
         array('backgroundcolor' => null, // null -> 'use theme default'
               'contentcolor' => null,