diff --git a/src/workflow/ArcanistDiffWorkflow.php b/src/workflow/ArcanistDiffWorkflow.php
--- a/src/workflow/ArcanistDiffWorkflow.php
+++ b/src/workflow/ArcanistDiffWorkflow.php
@@ -1962,7 +1962,13 @@
       $faux_message[] = pht('CC: %s', $this->getArgument('cc'));
     }
 
+    // See T12069. After T10312, the first line of a message is always parsed
+    // as a title. Add a placeholder so "Reviewers" and "CC" are never the
+    // first line.
+    $placeholder_title = pht('<placeholder>');
+
     if ($faux_message) {
+      array_unshift($faux_message, $placeholder_title);
       $faux_message = implode("\n\n", $faux_message);
       $local = array(
         '(Flags)     ' => array(
@@ -2034,6 +2040,10 @@
         continue;
       }
 
+      if ($title === $placeholder_title) {
+        continue;
+      }
+
       if (!isset($result['title'])) {
         // We don't have a title yet, so use this one.
         $result['title'] = $title;