diff -u b/core/lib/Drupal/Core/Render/Renderer.php b/core/lib/Drupal/Core/Render/Renderer.php
--- b/core/lib/Drupal/Core/Render/Renderer.php
+++ b/core/lib/Drupal/Core/Render/Renderer.php
@@ -216,20 +216,20 @@
       // A non-empty #children property takes precedence. This happens only if
       // it has been manually set into the render array.
       if (!empty($elements['#children'])) {
-        $children = ['#children'];
+        $children_keys = ['#children'];
       }
       else {
-        $children = Element::children($elements);
-      }
+        $children_keys = Element::children($elements);
 
-      if (empty($children)) {
-        return '';
+        if (empty($children_keys)) {
+          return '';
+        }
       }
 
       // Remove all elements except the children because the main level has been
-      // already rendered when the #render_children is set, and therefore they
-      // shouldn't have any effect on the render children.
-      $new_elements = array_intersect_key($elements, array_flip($children));
+      // already rendered when the #render_children is set and therefore they
+      // should not have any effect on the render children.
+      $new_elements = array_intersect_key($elements, array_flip($children_keys));
       // Create a new variable that references the render array that was passed
       // in. This allows the markup and cache information to be attached after
       // rendering the new elements array.
@@ -539,12 +539,10 @@
 
     $elements['#markup'] = Markup::create($prefix . $elements['#children'] . $suffix);
 
-    // #cache, #attached and #markup values should be always saved to the
-    // referenced elements variable to prevent re-rendering.
+    // #markup should be always saved to the referenced elements variable to
+    // prevent re-rendering.
     if (isset($original_elements)) {
       $original_elements['#markup'] = $elements['#markup'];
-      $original_elements['#attached'] = $elements['#attached'];
-      $original_elements['#cache'] = CacheableMetadata::createFromRenderArray($elements['#cache']);
     }
 
     // We've rendered this element (and its subtree!), now update the context.
diff -u b/core/tests/Drupal/KernelTests/Core/Render/RenderTest.php b/core/tests/Drupal/KernelTests/Core/Render/RenderTest.php
--- b/core/tests/Drupal/KernelTests/Core/Render/RenderTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/RenderTest.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\KernelTests\Core\Render;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
diff -u b/core/tests/Drupal/Tests/Core/Render/RendererTest.php b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
--- b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererTest.php
@@ -558,6 +558,17 @@
 
     // We don't want to reprint already printed render arrays.
     $this->assertEquals('', $this->renderer->renderRoot($build));
+
+    $build = [
+      'child' => [
+        '#markup' => 'kittens',
+      ],
+    ];
+    $this->assertEquals('kittens', $this->renderer->renderRoot($build));
+    $this->assertTrue($build['#printed']);
+
+    // We don't want to reprint already printed render arrays.
+    $this->assertEquals('', $this->renderer->renderRoot($build));
   }
 
   /**