diff --git a/src/aphront/response/AphrontHTMLResponse.php b/src/aphront/response/AphrontHTMLResponse.php
--- a/src/aphront/response/AphrontHTMLResponse.php
+++ b/src/aphront/response/AphrontHTMLResponse.php
@@ -6,6 +6,11 @@
     $headers = array(
       array('Content-Type', 'text/html; charset=UTF-8'),
     );
+    $cdn = PhabricatorEnv::getEnvConfig('security.alternate-file-domain');
+    if ($cdn) {
+      $headers[] = array('Link', '<'.$cdn.'>; rel="preconnect"');
+    }
+
     $headers = array_merge(parent::getHeaders(), $headers);
     return $headers;
   }