diff --git a/core/includes/common.inc b/core/includes/common.inc
index ee399a4..f5d1ff9 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -3633,7 +3633,7 @@ function drupal_render_cache_get(array $elements) {
  *
  * @see drupal_render_cache_get()
  */
-function drupal_render_cache_set(&$markup, array $elements) {
+function drupal_render_cache_set(&$markup, $elements) {
   // Create the cache ID for the element.
   if (!\Drupal::request()->isMethodSafe() || !$cid = drupal_render_cid_create($elements)) {
     return FALSE;
@@ -3729,7 +3729,7 @@ function drupal_render_cache_generate_placeholder($callback, array &$context) {
  * @see drupal_render()
  * @see drupal_render_collect_post_render_cache
  */
-function _drupal_render_process_post_render_cache(array &$elements) {
+function _drupal_render_process_post_render_cache(&$elements) {
   if (isset($elements['#post_render_cache'])) {
     /** @var \Drupal\Core\Controller\ControllerResolverInterface $controller_resolver */
     $controller_resolver = \Drupal::service('controller_resolver');
@@ -3787,7 +3787,7 @@ function _drupal_render_process_post_render_cache(array &$elements) {
  * @see drupal_render()
  * @see _drupal_render_process_post_render_cache()
  */
-function drupal_render_collect_post_render_cache(array &$elements, array $callbacks = array(), $is_root_element = TRUE) {
+function drupal_render_collect_post_render_cache(&$elements, array $callbacks = array(), $is_root_element = TRUE) {
   // Try to fetch the prerendered element from cache, to determine
   // #post_render_cache callbacks for this element and all its children. If we
   // don't do this, then the #post_render_cache tokens will be re-generated, but
diff --git a/core/lib/Drupal/Core/Render/Element.php b/core/lib/Drupal/Core/Render/Element.php
index 501f2de..f4993c2 100644
--- a/core/lib/Drupal/Core/Render/Element.php
+++ b/core/lib/Drupal/Core/Render/Element.php
@@ -68,7 +68,7 @@ public static function child($key) {
    * @return array
    *   The array keys of the element's children.
    */
-  public static function children(array &$elements, $sort = FALSE) {
+  public static function children(&$elements, $sort = FALSE) {
     // Do not attempt to sort elements which have already been sorted.
     $sort = isset($elements['#sorted']) ? !$elements['#sorted'] : $sort;
 
@@ -77,7 +77,7 @@ public static function children(array &$elements, $sort = FALSE) {
     $sortable = FALSE;
     foreach ($elements as $key => $value) {
       if ($key === '' || $key[0] !== '#') {
-        if (is_array($value)) {
+        if (is_array($value) || is_object($value)) {
           $children[$key] = $value;
           if (isset($value['#weight'])) {
             $sortable = TRUE;
diff --git a/core/modules/system/src/Tests/Common/RenderTest.php b/core/modules/system/src/Tests/Common/RenderTest.php
index 7587af6..bf43051 100644
--- a/core/modules/system/src/Tests/Common/RenderTest.php
+++ b/core/modules/system/src/Tests/Common/RenderTest.php
@@ -11,6 +11,7 @@
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Render\Element;
 use Drupal\simpletest\DrupalUnitTestBase;
+use Drupal\common_test\RenderableArray;
 
 /**
  * Tests drupal_render().
@@ -282,6 +283,40 @@ function testDrupalRenderBasics() {
   }
 
   /**
+   * Tests the output drupal_render() using objects instead of arrays.
+   */
+  function testDrupalRenderArrayObjects() {
+    // Simplest case, a single object.
+    $types[] = array(
+      'name' => 'Simple renderable object',
+      'value' => new RenderableArray(array('#markup' => 'Hello World')),
+      'expected' => 'Hello World',
+    );
+    // Two renderable objects
+    $types[] = array(
+      'name' => 'Array with two renderable objects',
+      'value' => array(
+          'hello' => new RenderableArray(array('#markup' => 'Hello', '#suffix' => ' ')),
+          'world' => new RenderableArray(array('#markup' => 'World')),
+       ),
+      'expected' => 'Hello World',
+    );
+    // More complex, mixed nested objects and arrays
+    $render = new RenderableArray();
+    $render['hello'] = new RenderableArray(array('#markup' => 'Hello', '#suffix' => ' '));
+    $render['world'] = array('#markup' => 'World');
+    $types[] = array(
+      'name' => 'Nested renderable objects',
+      'value' => $render,
+      'expected' => 'Hello World',
+    );
+    foreach($types as $type) {
+      $this->assertIdentical(drupal_render($type['value']), $type['expected'], '"' . $type['name'] . '" input rendered correctly by drupal_render().');
+    }
+  }
+
+
+  /**
    * Tests sorting by weight.
    */
   function testDrupalRenderSorting() {
diff --git a/core/modules/system/tests/modules/common_test/src/RenderableArray.php b/core/modules/system/tests/modules/common_test/src/RenderableArray.php
new file mode 100644
index 0000000..e8d1d17
--- /dev/null
+++ b/core/modules/system/tests/modules/common_test/src/RenderableArray.php
@@ -0,0 +1,64 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\common_test\RenderableArray.
+ */
+
+namespace Drupal\common_test;
+
+/**
+ * Array like object to test rendering.
+ */
+class RenderableArray implements \IteratorAggregate, \ArrayAccess{
+
+  /**
+   * Contained elements and properties.
+   *
+   * @var array
+   */
+  protected $elements;
+
+  /**
+   * Construct from array.
+   */
+  public function __construct($elements = array()) {
+    $this->elements = $elements;
+  }
+
+  /**
+   * Implements ArrayAccess::offsetExists().
+   */
+  public function offsetExists($offset) {
+    return isset($this->elements[$offset]);
+  }
+
+  /**
+   * Implements ArrayAccess::offsetGet().
+   */
+  public function &offsetGet($offset) {
+    return $this->elements[$offset];
+  }
+
+  /**
+   * Implements ArrayAccess::offsetSet().
+   */
+  public function offsetSet($offset, $value) {
+    $this->elements[$offset] = $value;
+  }
+
+  /**
+   * Implements ArrayAccess::offsetUnset().
+   */
+  public function offsetUnset($offset) {
+    unset($this->elements[$offset]);
+  }
+
+  /**
+   * Implements IteratorAggregate::getIterator();
+   */
+  public function getIterator() {
+    return new \ArrayIterator($this->elements);
+  }
+
+}