diff -u b/core/modules/system/src/Tests/Theme/TwigTransTest.php b/core/modules/system/src/Tests/Theme/TwigTransTest.php
--- b/core/modules/system/src/Tests/Theme/TwigTransTest.php
+++ b/core/modules/system/src/Tests/Theme/TwigTransTest.php
@@ -138,9 +138,15 @@
       '{{ token }} was successfully translated and prefixed with "@".'
     );
 
+    // @see \Drupal\Core\Template\TwigNodeTrans::compileString()
     $this->assertRaw(
       'Y U NO LET ME XSS: &"<>',
-      '{{ token|passthrough }} was successfully translated and prefixed with "!".'
+      '{{ token|passthrough }} (unsafe) was successfully translated and prefixed with "!".'
+    );
+
+    $this->assertRaw(
+      'YAY XSS: <script></script>',
+      '{{ token|passthrough }} (safe) was successfully translated and prefixed with "!".'
     );
 
     $this->assertRaw(
@@ -256,6 +262,9 @@
 msgid "Admin filtered: !string"
 msgstr "Y U NO LET ME XSS: !string"
 
+msgid "Safe: !safe_string"
+msgstr "YAY XSS: !safe_string"
+
 msgid "Placeholder: %string"
 msgstr "PLAYSHOLDR: %string"
 
diff -u b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
--- b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
+++ b/core/modules/system/tests/modules/twig_theme_test/templates/twig_theme_test.trans.html.twig
@@ -55,0 +56,6 @@
+  {% trans %}
+    {# Note this should never be necessary: we can just print the safe string in the template directly. #}
+    Safe: {{ safe_string|passthrough }}
+  {% endtrans %}
+</div>
+<div>
only in patch2:
unchanged:
--- a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.module
+++ b/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.module
@@ -1,5 +1,7 @@
 <?php
 
+use Drupal\Core\Render\SafeString;
+
 /**
  * Implements hook_theme().
  */
@@ -12,7 +14,7 @@ function twig_theme_test_theme($existing, $type, $theme, $path) {
     'template' => 'twig_theme_test.php_variables',
   );
   $items['twig_theme_test_trans'] = array(
-    'variables' => array(),
+    'variables' => array('safe_string' => SafeString::create('<script></script>')),
     'template' => 'twig_theme_test.trans',
   );
   $items['twig_theme_test_placeholder_outside_trans'] = array(