diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -13,7 +13,7 @@
     'core.pkg.js' => '632fb8f5',
     'dark-console.pkg.js' => '187792c2',
     'differential.pkg.css' => '2d70b7b9',
-    'differential.pkg.js' => 'b289f75d',
+    'differential.pkg.js' => 'b35de23a',
     'diffusion.pkg.css' => '42c75c37',
     'diffusion.pkg.js' => 'a98c0bf7',
     'maniphest.pkg.css' => '35995d6d',
@@ -381,7 +381,7 @@
     'rsrc/js/application/dashboard/behavior-dashboard-tab-panel.js' => '0116d3e8',
     'rsrc/js/application/diff/DiffChangeset.js' => '9a713ba5',
     'rsrc/js/application/diff/DiffChangesetList.js' => '10726e6a',
-    'rsrc/js/application/diff/DiffInline.js' => '7b0bdd6d',
+    'rsrc/js/application/diff/DiffInline.js' => '02791ed9',
     'rsrc/js/application/diff/DiffPathView.js' => '8207abf9',
     'rsrc/js/application/diff/DiffTreeView.js' => '5d83623b',
     'rsrc/js/application/diff/behavior-preview-link.js' => 'f51e9c17',
@@ -778,7 +778,7 @@
     'phabricator-dashboard-css' => '5a205b9d',
     'phabricator-diff-changeset' => '9a713ba5',
     'phabricator-diff-changeset-list' => '10726e6a',
-    'phabricator-diff-inline' => '7b0bdd6d',
+    'phabricator-diff-inline' => '02791ed9',
     'phabricator-diff-path-view' => '8207abf9',
     'phabricator-diff-tree-view' => '5d83623b',
     'phabricator-drag-and-drop-file-upload' => '4370900d',
@@ -944,6 +944,9 @@
       'javelin-leader',
       'javelin-json',
     ),
+    '02791ed9' => array(
+      'javelin-dom',
+    ),
     '02cb4398' => array(
       'javelin-behavior',
       'javelin-dom',
@@ -1616,9 +1619,6 @@
       'phabricator-drag-and-drop-file-upload',
       'phabricator-textareautils',
     ),
-    '7b0bdd6d' => array(
-      'javelin-dom',
-    ),
     '7b139193' => array(
       'javelin-behavior',
       'javelin-stratcom',
diff --git a/src/infrastructure/diff/PhabricatorInlineCommentController.php b/src/infrastructure/diff/PhabricatorInlineCommentController.php
--- a/src/infrastructure/diff/PhabricatorInlineCommentController.php
+++ b/src/infrastructure/diff/PhabricatorInlineCommentController.php
@@ -215,6 +215,19 @@
         $view = $this->buildScaffoldForView($edit_dialog);
 
         return $this->newInlineResponse($inline, $view);
+      case 'cancel':
+        $inline = $this->loadCommentForEdit($this->getCommentID());
+
+        $inline->setIsEditing(false);
+
+        $content = $inline->getContent();
+        if (!strlen($content)) {
+          $this->deleteComment($inline);
+        } else {
+          $this->saveComment($inline);
+        }
+
+        return $this->buildEmptyResponse();
       case 'new':
       case 'reply':
       default:
diff --git a/webroot/rsrc/js/application/diff/DiffInline.js b/webroot/rsrc/js/application/diff/DiffInline.js
--- a/webroot/rsrc/js/application/diff/DiffInline.js
+++ b/webroot/rsrc/js/application/diff/DiffInline.js
@@ -647,12 +647,25 @@
       }
 
       this.setEditing(false);
-
       this.setInvisible(false);
 
+      var uri = this._getInlineURI();
+      var data = this._newRequestData('cancel');
+      var handler = JX.bind(this, this._onCancelResponse);
+
+      this.setLoading(true);
+
+      new JX.Request(uri, handler)
+        .setData(data)
+        .send();
+
       this._didUpdate(true);
     },
 
+    _onCancelResponse: function(response) {
+      this.setLoading(false);
+    },
+
     _readText: function(row) {
       var textarea;
       try {