diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 6be3c3f..765f554 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1900,21 +1900,18 @@ function theme_indentation($variables) {
   return $output;
 }
 
+
 /**
- * Returns HTML to wrap child elements in a container.
+ * Prepares variables for container templates.
  *
- * Used for grouped form items. Can also be used as a #theme_wrapper for any
- * renderable element, to surround it with a <div> and add attributes such as
- * classes or an HTML id.
+ * Default template: container.html.twig.
  *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
  *   - element: An associative array containing the properties of the element.
  *     Properties used: #id, #attributes, #children.
- *
- * @ingroup themeable
  */
-function theme_container($variables) {
+function template_preprocess_container(&$variables) {
   $element = $variables['element'];
   // Ensure #attributes is set.
   $element += array('#attributes' => array());
@@ -1929,7 +1926,8 @@ function theme_container($variables) {
     $element['#attributes']['class'][] = 'form-wrapper';
   }
 
-  return '<div' . new Attribute($element['#attributes']) . '>' . $element['#children'] . '</div>';
+  $variables['children'] = $element['#children'];
+  $variables['attributes'] = $element['#attributes'];
 }
 
 /**
@@ -2707,6 +2705,7 @@ function drupal_common_theme() {
     ),
     'container' => array(
       'render element' => 'element',
+      'template' => 'container',
     ),
   );
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Common/RenderElementTypesTest.php b/core/modules/system/lib/Drupal/system/Tests/Common/RenderElementTypesTest.php
index 9ba4bf4..a618409 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Common/RenderElementTypesTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Common/RenderElementTypesTest.php
@@ -50,7 +50,7 @@ function testContainer() {
           '#type' => 'container',
           '#markup' => 'foo',
         ),
-        'expected' => '<div>foo</div>',
+        'expected' => '<div>foo</div>' . "\n",
       ),
       // Container with a class.
       array(
@@ -62,7 +62,7 @@ function testContainer() {
             'class' => 'bar',
           ),
         ),
-        'expected' => '<div class="bar">foo</div>',
+        'expected' => '<div class="bar">foo</div>' . "\n",
       ),
       // Container with children.
       array(
@@ -73,7 +73,7 @@ function testContainer() {
             '#markup' => 'foo',
           ),
         ),
-        'expected' => '<div>foo</div>',
+        'expected' => '<div>foo</div>' . "\n",
       ),
     );
 
diff --git a/core/modules/system/templates/container.html.twig b/core/modules/system/templates/container.html.twig
new file mode 100644
index 0000000..933a201
--- /dev/null
+++ b/core/modules/system/templates/container.html.twig
@@ -0,0 +1,15 @@
+{#
+/**
+ * @file
+ * Default theme implementation of a container used to wrap child elements.
+ *
+ * Available variables:
+ * - attributes: HTML attributes for the containing element.
+ * - children: The rendered child elements of the container.
+ *
+ * @see template_preprocess_container()
+ *
+ * @ingroup themeable
+ */
+#}
+<div{{ attributes }}>{{ children }}</div>