diff --git a/src/infrastructure/markup/PhabricatorMarkupOneOff.php b/src/infrastructure/markup/PhabricatorMarkupOneOff.php
--- a/src/infrastructure/markup/PhabricatorMarkupOneOff.php
+++ b/src/infrastructure/markup/PhabricatorMarkupOneOff.php
@@ -17,6 +17,7 @@
   private $content;
   private $preserveLinebreaks;
   private $engineRuleset;
+  private $disableCache;
 
   public function setEngineRuleset($engine_ruleset) {
     $this->engineRuleset = $engine_ruleset;
@@ -41,6 +42,15 @@
     return $this->content;
   }
 
+  public function setDisableCache($disable_cache) {
+    $this->disableCache = $disable_cache;
+    return $this;
+  }
+
+  public function getDisableCache() {
+    return $this->disableCache;
+  }
+
   public function getMarkupFieldKey($field) {
     return PhabricatorHash::digestForIndex($this->getContent()).':oneoff';
   }
@@ -74,6 +84,10 @@
   }
 
   public function shouldUseMarkupCache($field) {
+    if ($this->getDisableCache()) {
+      return false;
+    }
+
     return true;
   }
 
diff --git a/src/infrastructure/markup/PhabricatorMarkupPreviewController.php b/src/infrastructure/markup/PhabricatorMarkupPreviewController.php
--- a/src/infrastructure/markup/PhabricatorMarkupPreviewController.php
+++ b/src/infrastructure/markup/PhabricatorMarkupPreviewController.php
@@ -12,6 +12,7 @@
     $output = PhabricatorMarkupEngine::renderOneObject(
       id(new PhabricatorMarkupOneOff())
         ->setPreserveLinebreaks(true)
+        ->setDisableCache(true)
         ->setContent($text),
       'default',
       $viewer);