diff --git a/src/infrastructure/markup/PhabricatorMarkupEngine.php b/src/infrastructure/markup/PhabricatorMarkupEngine.php
--- a/src/infrastructure/markup/PhabricatorMarkupEngine.php
+++ b/src/infrastructure/markup/PhabricatorMarkupEngine.php
@@ -470,6 +470,7 @@
 
     $blocks = array();
     $blocks[] = new PhutilRemarkupEngineRemarkupQuotesBlockRule();
+    $blocks[] = new PhutilRemarkupEngineRemarkupReplyBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupLiteralBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupHeaderBlockRule();
     $blocks[] = new PhutilRemarkupEngineRemarkupHorizontalRuleBlockRule();
diff --git a/webroot/rsrc/css/core/remarkup.css b/webroot/rsrc/css/core/remarkup.css
--- a/webroot/rsrc/css/core/remarkup.css
+++ b/webroot/rsrc/css/core/remarkup.css
@@ -163,6 +163,10 @@
   font-style: normal;
 }
 
+.phabricator-remarkup blockquote div.remarkup-reply-head {
+  font-weight: bold;
+}
+
 .phabricator-remarkup img.remarkup-proxy-image {
   max-width: 640px;
   max-height: 640px;