diff --git a/core/themes/engines/twig/twig.engine b/core/themes/engines/twig/twig.engine
index d318263..d98f021 100644
--- a/core/themes/engines/twig/twig.engine
+++ b/core/themes/engines/twig/twig.engine
@@ -31,22 +31,49 @@ function twig_init($template) {
 }
 
 /**
- * Render twig templates.
+ * Renders a Twig template.
  *
- * This retrieves the Twig_Environment from the Drupal Injection container and
- * renders the template.
+ * This retrieves Twig_Environment from the container and renders the template.
+ *
+ * If Twig debug settings are enabled, HTML comments including file name
+ * suggestions will surround the template markup.
  *
  * @param $template_file
- *   The filename of the template to render.
+ *   The file name of the template to render.
  * @param $variables
  *   A keyed array of variables that will appear in the output.
  *
  * @return
- *   The output generated by the template.
+ *   The output generated by the template, plus any debug information.
  */
 function twig_render_template($template_file, $variables) {
   $variables['_references'] = array();
-  return drupal_container()->get('twig')->loadTemplate($template_file)->render($variables);
+  $output = array(
+    'debug_prefix'    => '',
+    'debug_info'      => '',
+    'rendered_markup' => drupal_container()->get('twig')->loadTemplate($template_file)->render($variables),
+    'debug_suffix'    => '',
+  );
+  if (settings()->get('twig_debug', FALSE)) {
+    $output['debug_prefix'] .= "\n\n<!-- THEME DEBUG -->";
+    $output['debug_prefix'] .= "\n<!-- CALL: theme('{$variables['theme_hook_original']}') -->";
+    if (!empty($variables['theme_hook_suggestions'])) {
+      $extension = twig_extension();
+      $current_template = explode('/', $template_file);
+      $current_template = array_pop($current_template);
+      $suggestions = $variables['theme_hook_suggestions'];
+      $suggestions[] = $variables['theme_hook_original'];
+      foreach ($suggestions as $key => &$suggestion) {
+        $template = $suggestion . $extension;
+        $prefix = ($template == $current_template) ? 'x' : '*';
+        $suggestion = $prefix . ' ' . str_replace('_', '-', $template);
+      }
+      $output['debug_info'] .= "\n<!-- FILE NAME SUGGESTIONS:\n   " . implode("\n   ", $suggestions) . "\n -->";
+    }
+    $output['debug_info']   .= "\n<!-- BEGIN OUTPUT from '{$template_file}'  -->\n";
+    $output['debug_suffix'] .= "\n<!-- END OUTPUT from '{$template_file}' -->\n\n";
+  }
+  return implode('', $output);
 }
 
 /**