diff --git a/core/includes/common.inc b/core/includes/common.inc
index bc6fac6..fbfc99a 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -413,7 +413,9 @@ function drupal_add_feed($url = NULL, $title = '') {
  */
 function drupal_get_feeds($delimiter = "\n") {
   $feeds = drupal_add_feed();
-  return drupal_mark_safe(implode($feeds, $delimiter));
+  $string = implode($feeds, $delimiter);
+  $GLOBALS['safe_strings'][$string] = TRUE;
+  return $string;
 }
 
 /**
@@ -3918,7 +3920,7 @@ function drupal_render(&$elements) {
 
   $prefix = isset($elements['#prefix']) ? $elements['#prefix'] : '';
   $suffix = isset($elements['#suffix']) ? $elements['#suffix'] : '';
-  $output = ($prefix) . $elements['#children'] . ($suffix);
+  $output = $prefix . $elements['#children'] . $suffix;
 
   // Cache the processed element if #cache is set.
   if (isset($elements['#cache'])) {
diff --git a/core/lib/Drupal/Component/Utility/String.php b/core/lib/Drupal/Component/Utility/String.php
index 81968b3..182518c 100644
--- a/core/lib/Drupal/Component/Utility/String.php
+++ b/core/lib/Drupal/Component/Utility/String.php
@@ -107,7 +107,9 @@ public static function format($string, array $args = array()) {
           // Pass-through.
       }
     }
-    return drupal_mark_safe(strtr($string, $args));
+    $output = strtr($string, $args);
+    $GLOBALS['safe_strings'][$output] = TRUE;
+    return $output;
   }
 
   /**
diff --git a/core/lib/Drupal/Component/Utility/Xss.php b/core/lib/Drupal/Component/Utility/Xss.php
index 7b0780e..3600825 100644
--- a/core/lib/Drupal/Component/Utility/Xss.php
+++ b/core/lib/Drupal/Component/Utility/Xss.php
@@ -71,7 +71,7 @@ public static function filter($string, $allowed_tags = array('a', 'em', 'strong'
     // Named entities.
     $string = preg_replace('/&([A-Za-z][A-Za-z0-9]*;)/', '&\1', $string);
 
-    return drupal_mark_safe(preg_replace_callback('%
+    $output = preg_replace_callback('%
       (
       <(?=[^a-zA-Z!/])  # a lone <
       |                 # or
@@ -80,7 +80,9 @@ public static function filter($string, $allowed_tags = array('a', 'em', 'strong'
       <[^>]*(>|$)       # a string that starts with a <, up until the > or the end of the string
       |                 # or
       >                 # just a >
-      )%x', '\Drupal\Component\Utility\Xss::split', $string));
+      )%x', '\Drupal\Component\Utility\Xss::split', $string);
+    $GLOBALS['safe_strings'][$output] = TRUE;
+    return $output;
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Template/TwigExtension.php b/core/lib/Drupal/Core/Template/TwigExtension.php
index 7425e90..c8aff5b 100644
--- a/core/lib/Drupal/Core/Template/TwigExtension.php
+++ b/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -41,7 +41,7 @@ public function getFilters() {
       'passthrough' => new \Twig_Filter_Function('twig_raw_filter'),
       'placeholder' => new \Twig_Filter_Function('twig_raw_filter'),
       // Helper filter used to replace twig's original raw() filter.
-      'twig_raw' => 'twig_raw',
+      'twig_raw' => new \Twig_Filter_Function('twig_raw'),
     );
   }
 
diff --git a/core/modules/filter/filter.module b/core/modules/filter/filter.module
index 23b9db6..4ca3a13 100644
--- a/core/modules/filter/filter.module
+++ b/core/modules/filter/filter.module
@@ -712,7 +712,9 @@ function check_markup($text, $format_id = NULL, $langcode = '', $cache = FALSE,
     $cache_id = $format->format . ':' . $langcode . ':' . hash('sha256', $text);
     if ($cached = cache('filter')->get($cache_id)) {
       // @todo: The caller is responsible that this is really safe.
-      return drupal_mark_safe($cached->data);
+      $output = $cached->data;
+      $GLOBALS['safe_strings'][$output] = TRUE;
+      return $output;
     }
   }
 
@@ -754,7 +756,8 @@ function check_markup($text, $format_id = NULL, $langcode = '', $cache = FALSE,
   }
 
   // @todo: The caller is responsible that this is really safe.
-  return drupal_mark_safe($text);
+  $GLOBALS['safe_strings'][$text] = TRUE;
+  return $text;
 }
 
 /**
diff --git a/core/themes/engines/twig/twig.engine b/core/themes/engines/twig/twig.engine
index bc7e75d..9891cd2 100644
--- a/core/themes/engines/twig/twig.engine
+++ b/core/themes/engines/twig/twig.engine
@@ -115,8 +115,8 @@ function twig_render_var($arg) {
     return $arg;
   }
 
-  // Treat output from RenderWrapper as safe, return a Twig_Markup instance.
-  if ($arg instanceof \Drupal\Core\Template\RenderWrapper) {
+  // For known objects with __toString() methods, return a Twig_Markup instance.
+  if ($arg instanceof \Drupal\Core\Template\RenderWrapper || $arg instanceof \Drupal\Core\Template\Attribute) {
     return new Twig_Markup((string) $arg, 'UTF-8');
   }
 
diff --git a/core/vendor/twig/twig/lib/Twig/Extension/Core.php b/core/vendor/twig/twig/lib/Twig/Extension/Core.php
index fa92f5e..898eff4 100644
--- a/core/vendor/twig/twig/lib/Twig/Extension/Core.php
+++ b/core/vendor/twig/twig/lib/Twig/Extension/Core.php
@@ -847,7 +847,9 @@ function twig_in_filter($value, $compare)
  */
 function twig_escape_filter(Twig_Environment $env, $string, $strategy = 'html', $charset = null, $autoescape = false)
 {
-    if ($autoescape && $string instanceof Twig_Markup) {
+    // @todo Create upstream pull request to remove unneeded is_object() call
+    //   for speed. Would be nice to profile this as well.
+    if ($autoescape && is_object($string) && $string instanceof Twig_Markup) {
         return $string;
     }