diff --git a/core/lib/Drupal/Core/Theme/ThemeManager.php b/core/lib/Drupal/Core/Theme/ThemeManager.php
index 31c10a7..b55a729 100644
--- a/core/lib/Drupal/Core/Theme/ThemeManager.php
+++ b/core/lib/Drupal/Core/Theme/ThemeManager.php
@@ -148,6 +148,7 @@ public function render($hook, array $variables) {
 
     // If an array of hook candidates were passed, use the first one that has an
     // implementation.
+    $theme_hook_candidates = is_array($hook) ? $hook : array($hook);
     if (is_array($hook)) {
       foreach ($hook as $candidate) {
         if ($theme_registry->has($candidate)) {
@@ -217,6 +218,7 @@ public function render($hook, array $variables) {
     // Supply original caller info.
     $variables += array(
       'theme_hook_original' => $original_hook,
+      'theme_hook_candidates' => $theme_hook_candidates,
     );
 
     // Set base hook for later use. For example if '#theme' => 'node__article'
diff --git a/core/themes/engines/twig/twig.engine b/core/themes/engines/twig/twig.engine
index af5ebe7..c4f5145 100644
--- a/core/themes/engines/twig/twig.engine
+++ b/core/themes/engines/twig/twig.engine
@@ -75,6 +75,14 @@ function twig_render_template($template_file, array $variables) {
   if ($twig_service->isDebug()) {
     $output['debug_prefix'] .= "\n\n<!-- THEME DEBUG -->";
     $output['debug_prefix'] .= "\n<!-- THEME HOOK: '" . SafeMarkup::checkPlain($variables['theme_hook_original']) . "' -->";
+    if (count($variables['theme_hook_candidates']) > 1) {
+      $candidates = array();
+      foreach ($variables['theme_hook_candidates'] as $candidate) {
+        $prefix = ($variables['theme_hook_original'] == $candidate) ? 'x' : '*';
+        $candidates[] = $prefix . ' ' . $candidate;
+      }
+      $output['debug_prefix'] .= "\n<!-- THEME HOOK CANDIDATES:\n   " . SafeMarkup::checkPlain(implode("\n   ", $candidates)) . "' -->";
+    }
     // If there are theme suggestions, reverse the array so more specific
     // suggestions are shown first.
     if (!empty($variables['theme_hook_suggestions'])) {