diff --git a/core/lib/Drupal/Core/Controller/DialogController.php b/core/lib/Drupal/Core/Controller/DialogController.php
index c8478f8..3340328 100644
--- a/core/lib/Drupal/Core/Controller/DialogController.php
+++ b/core/lib/Drupal/Core/Controller/DialogController.php
@@ -11,6 +11,7 @@
 use Drupal\Core\Ajax\OpenDialogCommand;
 use Symfony\Cmf\Component\Routing\RouteObjectInterface;
 use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\HttpKernelInterface;
 
 /**
@@ -63,11 +64,25 @@ public function dialog(Request $request, $_content, $modal = FALSE) {
     $callable = $this->controllerResolver->createController($_content);
     $arguments = $this->controllerResolver->getArguments($request, $callable);
     $controller_response = call_user_func_array($callable, $arguments);
-    if ($controller_response->isOk()) {
-      $content = $controller_response->getContent();
-      // @todo Remove use of drupal_get_title() when
-      //  http://drupal.org/node/1871596 is in.
-      $title = drupal_get_title();
+
+    if ($controller_response instanceof Response) {
+      return $controller_response;
+    }
+    else {
+      if (!is_array($controller_response)) {
+        $content = array(
+          '#markup' => $controller_response,
+        );
+      }
+      else {
+        $content = $controller_response;
+      }
+
+      // If no title was returned fall back to one defined in the route.
+      if (!isset($content['#title']) && $request->attributes->has('_title')) {
+        $content['#title'] = $request->attributes->get('_title');
+      }
+
       $response = new AjaxResponse();
       // Fetch any modal options passed in from data-dialog-options.
       if (!($options = $request->request->get('dialogOptions'))) {
@@ -96,7 +111,7 @@ public function dialog(Request $request, $_content, $modal = FALSE) {
           $target = '#' . drupal_html_id("drupal-dialog-$route_name");
         }
       }
-      $response->addCommand(new OpenDialogCommand($target, $title, $content, $options));
+      $response->addCommand(new OpenDialogCommand($target, isset($content['#title']) ? $content['#title'] : '', drupal_render($content), $options));
       return $response;
     }
     // An error occurred in the subrequest, return that.
diff --git a/core/modules/system/tests/modules/ajax_test/ajax_test.module b/core/modules/system/tests/modules/ajax_test/ajax_test.module
index e358018..3217c41 100644
--- a/core/modules/system/tests/modules/ajax_test/ajax_test.module
+++ b/core/modules/system/tests/modules/ajax_test/ajax_test.module
@@ -269,8 +269,14 @@ function _ajax_test_dialog($is_modal = FALSE) {
 
 /**
  * Returns example content for dialog tests.
+ *
+ * @param string $title
+ *   (optional) The title of the dialog result.
+ *
+ * @return array
+ *   A render array as expected by drupal_render().
  */
-function ajax_test_dialog_contents() {
+function ajax_test_dialog_contents($title = '') {
   // This is a regular render array; the keys do not have special meaning.
   $content = array(
     'content' => array(
@@ -288,6 +294,10 @@ function ajax_test_dialog_contents() {
     ),
   );
 
+  if ($title) {
+    $content['#title'] = $title;
+  }
+
   return $content;
 }
 
diff --git a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestController.php b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestController.php
index 53044c5..91d44a1 100644
--- a/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestController.php
+++ b/core/modules/system/tests/modules/ajax_test/lib/Drupal/ajax_test/AjaxTestController.php
@@ -17,8 +17,7 @@ class AjaxTestController {
    */
   public function dialogContents() {
     // Re-use the utility method that returns the example content.
-    drupal_set_title(t('AJAX Dialog contents'));
-    return ajax_test_dialog_contents();
+    return ajax_test_dialog_contents(t('AJAX Dialog contents'));
   }
 
 }