diff --git a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
index 20ccc2b..22ed1b2 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Theme/ThemeTest.php
@@ -194,6 +194,20 @@ function testRegistryRebuild() {
   }
 
   /**
+   * Tests automatic drupal_render_children() for 'render element' theme hooks.
+   */
+  function testDrupalRenderChildren() {
+    $element = array(
+      '#theme' => 'theme_test_render_element_children',
+      'child' => array(
+        '#markup' => 'Foo',
+      ),
+    );
+
+    $this->assertIdentical(theme('theme_test_render_element_children', $element), 'Foo', 'drupal_render() calls drupal_render_children() when rendering a render element.');
+  }
+
+  /**
    * Tests theme can provide classes.
    */
   function testClassLoading() {
diff --git a/core/modules/system/tests/modules/theme_test/theme_test.module b/core/modules/system/tests/modules/theme_test/theme_test.module
index 137fdfc..c35f964 100644
--- a/core/modules/system/tests/modules/theme_test/theme_test.module
+++ b/core/modules/system/tests/modules/theme_test/theme_test.module
@@ -17,6 +17,9 @@ function theme_test_theme($existing, $type, $theme, $path) {
   $items['theme_test_foo'] = array(
     'variables' => array('foo' => NULL),
   );
+  $items['theme_test_render_element_children'] = array(
+    'render element' => 'element',
+  );
   return $items;
 }
 
@@ -172,3 +175,17 @@ function theme_theme_test_foo($variables) {
   return $variables['foo'];
 }
 
+/**
+ * Theme function for testing automatic drupal_render_children() behaviour.
+ *
+ * Theme hooks defining a 'render element' add an internal '#render_children'
+ * property. When this property is found, drupal_render() returns
+ * drupal_render_children() to prevent infinite recursion.
+ *
+ * @param array $variables
+ *   An associative array containing:
+ *   - element: An associative array containing the properties of the element.
+ */
+function theme_theme_test_render_element_children($variables) {
+  return drupal_render($variables['element']);
+}