diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index 697f8c7..ac380ef 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -207,7 +207,9 @@ function theme_admin_page($variables) {
 }
 
 /**
- * Returns HTML for the output of the admin index page.
+ * Prepares variables for admin index template.
+ *
+ * Default template: system-admin-index.html.twig.
  *
  * @param $variables
  *   An associative array containing:
@@ -215,55 +217,35 @@ function theme_admin_page($variables) {
  *
  * @ingroup themeable
  */
-function theme_system_admin_index($variables) {
-  $menu_items = $variables['menu_items'];
-
-  $container = array('left' => '', 'right' => '');
-  $flip = array('left' => 'right', 'right' => 'left');
-  $position = 'left';
-
+function template_preprocess_system_admin_index(&$variables) {
+  $variables['system_compact_link'] = array(
+    '#theme' => 'system_compact_link'
+  );
+  $variables['containers'] = array();
+  $stripe = 0;
   // Iterate over all modules.
-  foreach ($menu_items as $module => $block) {
+  foreach ($variables['menu_items'] as $module => $block) {
     list($description, $items) = $block;
-
+    $position = ++$stripe % 2 ? 'left' : 'right';
     // Output links.
     if (count($items)) {
-      $admin_block_content = array(
-        '#theme' => 'admin_block_content',
-        '#content' => $items,
-      );
-      $block = array();
-      $block['title'] = $module;
-      $block['content'] = drupal_render($admin_block_content);
-      $block['description'] = t($description);
-      $block['show'] = TRUE;
 
-      $admin_block = array(
+      $variables['containers'][$position]['blocks'][] = array(
         '#theme' => 'admin_block',
-        '#block' => $block,
+        '#block' => array(
+          'position' => $position,
+          'title' => $module,
+          'show' => TRUE,
+          'content' => array(
+            '#theme' => 'admin_block_content',
+            '#content' => $items,
+          ),
+          'description' => t($description),
+        ),
       );
-      if ($block_output = drupal_render($admin_block)) {
-        if (!isset($block['position'])) {
-          // Perform automatic striping.
-          $block['position'] = $position;
-          $position = $flip[$position];
-        }
-        $container[$block['position']] .= $block_output;
-      }
-    }
-  }
 
-  $system_compact_link = array('#theme' => 'system_compact_link');
-  $output = '<div class="admin clearfix">';
-  $output .= drupal_render($system_compact_link);
-  foreach ($container as $id => $data) {
-    $output .= '<div class="' . $id . ' clearfix">';
-    $output .= $data;
-    $output .= '</div>';
+    }
   }
-  $output .= '</div>';
-
-  return $output;
 }
 
 /**
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index fc6f61c..94dce21 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -193,6 +193,7 @@ function system_theme() {
     'system_admin_index' => array(
       'variables' => array('menu_items' => NULL),
       'file' => 'system.admin.inc',
+      'template' => 'system-admin-index',
     ),
     'system_compact_link' => array(
       'variables' => array(),
diff --git a/core/modules/system/templates/system-admin-index.html.twig b/core/modules/system/templates/system-admin-index.html.twig
new file mode 100644
index 0000000..9b3282f
--- /dev/null
+++ b/core/modules/system/templates/system-admin-index.html.twig
@@ -0,0 +1,24 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the admin index page.
+ *
+ * Available variables:
+ * - system_compact_link: Themed link to toggle compact view.
+ * - container: Container for admin blocks.
+ *
+ * @see template_preprocess_system_admin_index()
+ *
+ * @ingroup themeable
+ */
+#}
+<div class="admin clearfix">
+  {{ system_compact_link }}
+  {% for position, container in containers %}
+    <div class="{{ position }} clearfix">
+      {% for block in container.blocks %}
+        {{ block }}
+      {% endfor %}
+    </div>
+  {% endfor %}
+</div>