diff --git a/src/aphront/response/AphrontResponse.php b/src/aphront/response/AphrontResponse.php
--- a/src/aphront/response/AphrontResponse.php
+++ b/src/aphront/response/AphrontResponse.php
@@ -110,6 +110,11 @@
 
     $headers[] = array('Referrer-Policy', 'no-referrer');
 
+    $cdn = PhabricatorEnv::getEnvConfig('security.alternate-file-domain');
+    if ($cdn) {
+      $headers[] = array('Link', '<'.$cdn.'>; rel="preconnect"');
+    }
+
     foreach ($this->headers as $header) {
       $headers[] = $header;
     }