diff --git a/core/modules/update/templates/update-last-check.html.twig b/core/modules/update/templates/update-last-check.html.twig
new file mode 100644
index 0000000..daaded6
--- /dev/null
+++ b/core/modules/update/templates/update-last-check.html.twig
@@ -0,0 +1,24 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the last time we checked for update data.
+ *
+ * Available variables:
+ * - last_checked: A boolean when the site last checked for available updates.
+ * - time: The time the site last checked for updates.
+ * - link: A link to check for updates manually.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_update_last_check()
+ *
+ * @ingroup themeable
+ */
+#}
+<div class="update checked">
+  {% if last_checked %}
+    {{ 'Last checked: @time ago'|t({'@time': time}) }}
+  {% else %}
+    {{ 'Last checked: never'|t }}
+  {% endif %}
+  <span class="check-manually">({{ link }})</span>
+</div>
diff --git a/core/modules/update/templates/update-report.html.twig b/core/modules/update/templates/update-report.html.twig
new file mode 100644
index 0000000..8e97022
--- /dev/null
+++ b/core/modules/update/templates/update-report.html.twig
@@ -0,0 +1,100 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the project status report.
+ *
+ * Available variables:
+ * - project_types: A list of product types.
+ *   - label: Project type label.
+ *   - projects: Data about each project's status.
+ *     - title: The project tile.
+ *     - attributes: HTML attributes for the product row.
+ *     - status_label: The project status label.
+ *     - reason: @todo.
+ *     - icon: The project status version indicator icon.
+ *     - existing_version: @todo.
+ *     - versions: @todo.
+ *     - install_type: @todo.
+ *     - datestamp: @todo.
+ *     - extra: @todo.
+ *       - attributes: HTML attributes for the extra items.
+ *       - label: @todo.
+ *       - data: @todo.
+ *     - includes: @todo.
+ *     - base_themes: @todo.
+ *     - sub_themes: @todo.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_update_report()
+ *
+ * @ingroup themeable
+ */
+#}
+{% for project_type in project_types %}
+  <h3>{{ project_type.label }}</h3>
+  <table class="update">
+    <tbody>
+      {% for project in project_type.projects %}
+        <tr{{ project.attributes }}>
+          <td>
+            {% spaceless %}
+            <div class="version-status">
+              {{- project.status_label|default(project.reason) -}}
+              <span class="icon">{{ project.icon }}</span>
+            </div>
+            {% endspaceless %}
+
+            <div class="project">{{ project.title }} {{ project.existing_version }}
+              {% if project.install_type == 'dev' and project.datestamp %}
+                <span class="version-date">({{ project.datestamp }})</span>
+              {% endif %}
+            </div>
+
+            {% if project.versions %}
+              <div class="versions">
+              {% for version in project.versions %}
+                {{ version }}
+              {% endfor %}
+              </div>
+            {% endif %}
+
+            <div class="info">
+              {% if project.extra %}
+                <div class="extra">
+                  {% for extra in project.extra %}
+                    <div{{ extra.attributes }}>
+                      {{ extra.label }}: {{ extra.data }}
+                    </div>
+                  {% endfor %}
+                </div>
+              {% endif %}
+              <div class="includes">
+                {% if project.disabled %}
+                  {{ 'Includes:'|t }}
+                  <ul>
+                    <li class="first odd">{{ 'Enabled: %includes'|t({'%includes': project.includes|join(', ')}) }}</li>
+                    <li class="last even">{{ 'Disabled: %disabled'|t({'%disabled': project.disabled|join(', ')}) }}</li>
+                  </ul>
+                {% else %}
+                  {{ 'Includes: %includes'|t({'%includes': project.includes|join(', ')}) }}
+                {% endif %}
+              </div>
+
+              {% if project.base_themes %}
+                <div class="basethemes">
+                {{ 'Depends on: !basethemes'|t({'!basethemes': project.base_themes|join(', ')}) }}
+              </div>
+              {% endif %}
+
+              {% if project.sub_themes %}
+                <div class="subthemes">
+                  {{ 'Required by: %subthemes'|t({'%subthemes': project.sub_themes|join(', ')}) }}
+                </div>
+              {% endif %}
+            </div>
+          </td>
+        </tr>
+      {% endfor %}
+    </tbody>
+  </table>
+{% endfor %}
diff --git a/core/modules/update/templates/update-status-label.html.twig b/core/modules/update/templates/update-status-label.html.twig
new file mode 100644
index 0000000..43c8512
--- /dev/null
+++ b/core/modules/update/templates/update-status-label.html.twig
@@ -0,0 +1,21 @@
+{#
+/**
+ * @file
+ * Default theme implementation for an update status label.
+ *
+ * Available variables:
+ * - text: The status label text.
+ * - attributes: Remaining HTML attributes for the element.
+ *   - class: HTML classes that can be used to style contextually through CSS.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_update_status_label()
+ *
+ * @ingroup themeable
+ */
+#}
+{% spaceless %}
+  {% if text %}
+    <span{{ attributes }}>{{ text|t }}</span>
+  {% endif %}
+{% endspaceless %}
diff --git a/core/modules/update/templates/update-version.html.twig b/core/modules/update/templates/update-version.html.twig
new file mode 100644
index 0000000..119a781
--- /dev/null
+++ b/core/modules/update/templates/update-version.html.twig
@@ -0,0 +1,30 @@
+{#
+/**
+ * @file
+ * Default theme implementation for the version display of a project.
+ *
+ * Available variables:
+ *   - attributes: HTML attributes for the update versions table.
+ *   - version_link: @todo.
+ *   - version_date: The date of the release.
+ *   - version_links: @todo.
+ *   - tag: The title of the project.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_update_version()
+ *
+ * @ingroup themeable
+ */
+#}
+<table{{ attributes }}>
+  <tr>
+    <td class="version-title">{{ tag }}</td>
+    <td class="version-details">
+      {{ version_link }}
+      <span class="version-date">({{ version_date }})</span>
+    </td>
+    <td class="version-links">
+      {{ version_links }}
+    </td>
+  </tr>
+</table>
diff --git a/core/modules/update/update.manager.inc b/core/modules/update/update.manager.inc
index bc84058..691d87c 100644
--- a/core/modules/update/update.manager.inc
+++ b/core/modules/update/update.manager.inc
@@ -67,7 +67,11 @@ function update_manager_update_form($form, $form_state = array(), $context) {
     return $form;
   }
 
-  $form['#theme'] = 'update_manager_update_form';
+  $last = state()->get('update.last_check') ?: 0;
+  $form['update_lask_check'] = array(
+    '#theme' => 'update_last_check',
+    '#last' => $last,
+  );
 
   $available = update_get_available(TRUE);
   if (empty($available)) {
@@ -268,23 +272,6 @@ function update_manager_update_form($form, $form_state = array(), $context) {
 }
 
 /**
- * Returns HTML for the first page in the process of updating projects.
- *
- * @param $variables
- *   An associative array containing:
- *   - form: A render element representing the form.
- *
- * @ingroup themeable
- */
-function theme_update_manager_update_form($variables) {
-  $form = $variables['form'];
-  $last = state()->get('update.last_check') ?: 0;
-  $output = theme('update_last_check', array('last' => $last));
-  $output .= drupal_render_children($form);
-  return $output;
-}
-
-/**
  * Form validation handler for update_manager_update_form().
  *
  * Ensures that at least one project is selected.
diff --git a/core/modules/update/update.module b/core/modules/update/update.module
index 7dee311..de034b5 100644
--- a/core/modules/update/update.module
+++ b/core/modules/update/update.module
@@ -257,21 +257,24 @@ function update_manager_access() {
  */
 function update_theme() {
   return array(
-    'update_manager_update_form' => array(
-      'render element' => 'form',
-      'file' => 'update.manager.inc',
-    ),
     'update_last_check' => array(
       'variables' => array('last' => NULL),
+      'template'  => 'update-last-check',
     ),
     'update_report' => array(
       'variables' => array('data' => NULL),
+      'file' => 'update.report.inc',
+      'template' => 'update-report',
     ),
     'update_version' => array(
       'variables' => array('version' => NULL, 'tag' => NULL, 'class' => array()),
+      'file' => 'update.report.inc',
+      'template' => 'update-version',
     ),
     'update_status_label' => array(
       'variables' => array('status' => NULL),
+      'file' => 'update.report.inc',
+      'template' => 'update-status-label',
     ),
   );
 }
@@ -625,13 +628,11 @@ function _update_project_status_sort($a, $b) {
  * @see theme_update_available_updates_form()
  * @ingroup themeable
  */
-function theme_update_last_check($variables) {
+function template_preprocess_update_last_check(&$variables) {
   $last = $variables['last'];
-  $output = '<div class="update checked">';
-  $output .= $last ? t('Last checked: @time ago', array('@time' => format_interval(REQUEST_TIME - $last))) : t('Last checked: never');
-  $output .= ' <span class="check-manually">(' . l(t('Check manually'), 'admin/reports/updates/check', array('query' => drupal_get_destination())) . ')</span>';
-  $output .= "</div>\n";
-  return $output;
+  $variables['last_checked'] = ($last != NULL);
+  $variables['time'] = format_interval(REQUEST_TIME - $last);
+  $variables['link'] = l(t('Check manually'), 'admin/reports/updates/check', array('query' => drupal_get_destination()));
 }
 
 /**
diff --git a/core/modules/update/update.report.inc b/core/modules/update/update.report.inc
index 607b523..973d4a1 100644
--- a/core/modules/update/update.report.inc
+++ b/core/modules/update/update.report.inc
@@ -1,5 +1,7 @@
 <?php
 
+use Drupal\Core\Template\Attribute;
+
 /**
  * @file
  * Code required only when rendering the available updates report.
@@ -11,37 +13,47 @@
  * @see update_menu()
  */
 function update_status() {
+  $build = array();
+  $last = state()->get('update.last_check') ?: 0;
+  $build['last_check'] = array(
+    '#theme' => 'update_last_check',
+    '#last' => $last,
+  );
   if ($available = update_get_available(TRUE)) {
     module_load_include('inc', 'update', 'update.compare');
     $data = update_calculate_project_data($available);
-    return theme('update_report', array('data' => $data));
   }
   else {
-    return theme('update_report', array('data' => _update_no_data()));
+    $data = _update_no_data();
   }
+
+  if (!is_array($data)) {
+    $build['data'] = array(
+      '#markup' => $data,
+      '#prefix' => '<p>',
+      '#suffix' => '</p>',
+    );
+    return $build;
+  }
+
+  $build['report'] = array(
+    '#theme' => 'update_report',
+    '#data' => $data,
+  );
+  return $build;
 }
 
 /**
- * Returns HTML for the project status report.
+ * Prepares variables the project status report.
+ *
+ * Default template: update-report.html.twig.
  *
  * @param array $variables
  *   An associative array containing:
  *   - data: An array of data about each project's status.
- *
- * @ingroup themeable
  */
-function theme_update_report($variables) {
+function template_preprocess_update_report(&$variables) {
   $data = $variables['data'];
-
-  $last = state()->get('update.last_check') ?: 0;
-  $output = theme('update_last_check', array('last' => $last));
-
-  if (!is_array($data)) {
-    $output .= '<p>' . $data . '</p>';
-    return $output;
-  }
-
-  $header = array();
   $rows = array();
 
   $notification_level = config('update.settings')->get('notification.threshold');
@@ -59,53 +71,97 @@ function theme_update_report($variables) {
     switch ($project['status']) {
       case UPDATE_CURRENT:
         $class = 'ok';
-        $icon = theme('image', array('uri' => 'core/misc/watchdog-ok.png', 'width' => 18, 'height' => 18, 'alt' => t('ok'), 'title' => t('ok')));
+        $icon = array(
+          '#theme' => 'image',
+          '#uri' => 'core/misc/watchdog-ok.png',
+          '#width' => 18,
+          '#height' => 18,
+          '#alt' => t('ok'),
+          '#title' => t('ok'),
+        );
         break;
       case UPDATE_UNKNOWN:
       case UPDATE_FETCH_PENDING:
       case UPDATE_NOT_FETCHED:
         $class = 'unknown';
-        $icon = theme('image', array('uri' => 'core/misc/watchdog-warning.png', 'width' => 18, 'height' => 18, 'alt' => t('warning'), 'title' => t('warning')));
+        $icon = array(
+          '#theme' => 'image',
+          '#uri' => 'core/misc/watchdog-warning.png',
+          '#width' => 18,
+          '#height' => 18,
+          '#alt' => t('warning'),
+          '#title' => t('warning'),
+        );
         break;
       case UPDATE_NOT_SECURE:
       case UPDATE_REVOKED:
       case UPDATE_NOT_SUPPORTED:
         $class = 'error';
-        $icon = theme('image', array('uri' => 'core/misc/watchdog-error.png', 'width' => 18, 'height' => 18, 'alt' => t('error'), 'title' => t('error')));
+        $icon = array(
+          '#theme' => 'image',
+          '#uri' => 'core/misc/watchdog-error.png',
+          '#width' => 18,
+          '#height' => 18,
+          '#alt' => t('error'),
+          '#title' => t('error'),
+        );
         break;
       case UPDATE_NOT_CHECKED:
       case UPDATE_NOT_CURRENT:
       default:
         $class = 'warning';
-        $icon = theme('image', array('uri' => 'core/misc/watchdog-warning.png', 'width' => 18, 'height' => 18, 'alt' => t('warning'), 'title' => t('warning')));
+        $icon = array(
+          '#theme' => 'image',
+          '#uri' => 'core/misc/watchdog-warning.png',
+          '#width' => 18,
+          '#height' => 18,
+          '#alt' => t('warning'),
+          '#title' => t('warning'),
+        );
         break;
     }
 
-    $row = '<div class="version-status">';
-    $status_label = theme('update_status_label', array('status' => $project['status']));
-    $row .= !empty($status_label) ? $status_label : check_plain($project['reason']);
-    $row .= '<span class="icon">' . $icon . '</span>';
-    $row .= "</div>\n";
+    // Used to collect the project values.
+    $row = array();
+    $row['attributes'] = new Attribute(array('class' => $class));
+    $row['icon'] = $icon;
+
+    // Rendered status label here because we can't check that a TwigReference
+    // is empty in the twig file.
+    $status_label = array(
+      '#theme' => 'update_status_label',
+      '#status' => $project['status'],
+    );
+    $row['status_label'] = drupal_render($status_label);
+
+    if (!empty($project['reason'])) {
+      $row['reason'] = check_plain($project['reason']);
+    }
+    else {
+      $row['reason'] = '';
+    }
 
-    $row .= '<div class="project">';
+    // Set the project title.
     if (isset($project['title'])) {
       if (isset($project['link'])) {
-        $row .= l($project['title'], $project['link']);
+        $row['title'] = l($project['title'], $project['link']);
       }
       else {
-        $row .= check_plain($project['title']);
+        $row['title'] = check_plain($project['title']);
       }
     }
     else {
-      $row .= check_plain($project['name']);
+      $row['title'] = check_plain($project['name']);
     }
-    $row .= ' ' . check_plain($project['existing_version']);
+
+    // Clean up the version for twig.
+    $row['existing_version'] = check_plain($project['existing_version']);
+
     if ($project['install_type'] == 'dev' && !empty($project['datestamp'])) {
-      $row .= ' <span class="version-date">(' . format_date($project['datestamp'], 'custom', 'Y-M-d') . ')</span>';
+      $row['datestamp'] = format_date($project['datestamp'], 'custom', 'Y-M-d');
     }
-    $row .= "</div>\n";
 
-    $versions_inner = '';
+    $versions_inner = array();
     $security_class = array();
     $version_class = array();
     if (isset($project['recommended'])) {
@@ -115,7 +171,10 @@ function theme_update_report($variables) {
         // If there's only 1 security update and it has the same version we're
         // recommending, give it the same CSS class as if it was recommended,
         // but don't print out a separate "Recommended" line for this project.
-        if (!empty($project['security updates']) && count($project['security updates']) == 1 && $project['security updates'][0]['version'] === $project['recommended']) {
+        if (!empty($project['security updates'])
+            && count($project['security updates']) == 1
+            && $project['security updates'][0]['version'] === $project['recommended']
+            ) {
           $security_class[] = 'version-recommended';
           $security_class[] = 'version-recommended-strong';
         }
@@ -134,68 +193,87 @@ function theme_update_report($variables) {
               ) {
             $version_class[] = 'version-recommended-strong';
           }
-          $versions_inner .= theme('update_version', array('version' => $project['releases'][$project['recommended']], 'tag' => t('Recommended version:'), 'class' => $version_class));
+          $versions_inner[] = array(
+            '#theme' => 'update_version',
+            '#version' => $project['releases'][$project['recommended']],
+            '#tag' => t('Recommended version:'),
+            '#class' => $version_class,
+          );
         }
 
         // Now, print any security updates.
         if (!empty($project['security updates'])) {
           $security_class[] = 'version-security';
           foreach ($project['security updates'] as $security_update) {
-            $versions_inner .= theme('update_version', array('version' => $security_update, 'tag' => t('Security update:'), 'class' => $security_class));
+            $versions_inner[] = array(
+              '#theme' => 'update_version',
+              '#version' => $security_update,
+              '#tag' => t('Security update:'),
+              '#class' => $security_class,
+            );
           }
         }
       }
 
       if ($project['recommended'] !== $project['latest_version']) {
-        $versions_inner .= theme('update_version', array('version' => $project['releases'][$project['latest_version']], 'tag' => t('Latest version:'), 'class' => array('version-latest')));
+        $versions_inner[] = array(
+          '#theme' => 'update_version',
+          '#version' => $project['releases'][$project['latest_version']],
+          '#tag' => t('Latest version:'),
+          '#class' => array('version-latest'),
+        );
       }
       if ($project['install_type'] == 'dev'
           && $project['status'] != UPDATE_CURRENT
           && isset($project['dev_version'])
           && $project['recommended'] !== $project['dev_version']) {
-        $versions_inner .= theme('update_version', array('version' => $project['releases'][$project['dev_version']], 'tag' => t('Development version:'), 'class' => array('version-latest')));
+        $versions_inner[] = array(
+          '#theme' => 'update_version',
+          '#version' => $project['releases'][$project['dev_version']],
+          '#tag' => t('Development version:'),
+          '#class' => array('version-latest'),
+        );
       }
     }
 
     if (isset($project['also'])) {
       foreach ($project['also'] as $also) {
-        $versions_inner .= theme('update_version', array('version' => $project['releases'][$also], 'tag' => t('Also available:'), 'class' => array('version-also-available')));
+        $versions_inner[] = array(
+          '#theme' => 'update_version',
+          '#version' => $project['releases'][$also],
+          '#tag' => t('Also available:'),
+          '#class' => array('version-also-available'),
+        );
       }
     }
 
     if (!empty($versions_inner)) {
-      $row .= "<div class=\"versions\">\n" . $versions_inner . "</div>\n";
+      $row['versions'] = $versions_inner;
     }
-    $row .= "<div class=\"info\">\n";
+
+    $row['extra'] = array();
     if (!empty($project['extra'])) {
-      $row .= '<div class="extra">' . "\n";
       foreach ($project['extra'] as $key => $value) {
-        $row .= '<div class="' . implode(' ', $value['class']) . '">';
-        $row .= check_plain($value['label']) . ': ';
-        $row .= drupal_placeholder($value['data']);
-        $row .= "</div>\n";
+        $extra_item = array();
+        $extra_item['attributes'] = new Attribute(array('class' => $value['class']));
+        $extra_item['label'] = check_plain($value['label']);
+        $extra_item['data'] = drupal_placeholder($value['data']);
+        $row['extra'][$key] = $extra_item;
       }
-      $row .= "</div>\n";  // extra div.
     }
 
-    $row .= '<div class="includes">';
-    sort($project['includes']);
+    // Make sure we start with a clean slate for each project in the report.
+    $row['disabled'] = array();
+    $row['includes'] = array();
     if (!empty($project['disabled'])) {
       sort($project['disabled']);
-      // Make sure we start with a clean slate for each project in the report.
-      $includes_items = array();
-      $row .= t('Includes:');
-      $includes_items[] = t('Enabled: %includes', array('%includes' => implode(', ', $project['includes'])));
-      $includes_items[] = t('Disabled: %disabled', array('%disabled' => implode(', ', $project['disabled'])));
-      $row .= theme('item_list', array('items' => $includes_items));
+      $row['disabled'] = $project['disabled'];
     }
-    else {
-      $row .= t('Includes: %includes', array('%includes' => implode(', ', $project['includes'])));
-    }
-    $row .= "</div>\n";
+
+    sort($project['includes']);
+    $row['includes'] = $project['includes'];
 
     if (!empty($project['base_themes'])) {
-      $row .= '<div class="basethemes">';
       asort($project['base_themes']);
       $base_themes = array();
       foreach ($project['base_themes'] as $base_key => $base_theme) {
@@ -203,34 +281,34 @@ function theme_update_report($variables) {
           case UPDATE_NOT_SECURE:
           case UPDATE_REVOKED:
           case UPDATE_NOT_SUPPORTED:
-            $base_themes[] = t('%base_theme (!base_label)', array('%base_theme' => $base_theme, '!base_label' => theme('update_status_label', array('status' => $status[$base_key]))));
+            $status_label = array(
+              '#theme' => 'update_status_label',
+              '#status' => $status[$base_key],
+            );
+            $base_themes[] = t('%base_theme (!base_label)', array(
+              '%base_theme' => $base_theme,
+              '!base_label' => drupal_render($status_label),
+            ));
             break;
 
           default:
             $base_themes[] = drupal_placeholder($base_theme);
         }
       }
-      $row .= t('Depends on: !basethemes', array('!basethemes' => implode(', ', $base_themes)));
-      $row .= "</div>\n";
+      $row['base_themes'] = $base_themes;
     }
 
     if (!empty($project['sub_themes'])) {
-      $row .= '<div class="subthemes">';
       sort($project['sub_themes']);
-      $row .= t('Required by: %subthemes', array('%subthemes' => implode(', ', $project['sub_themes'])));
-      $row .= "</div>\n";
+      $row['sub_themes'] = $project['sub_themes'];
     }
 
-    $row .= "</div>\n"; // info div.
-
+    // Build project rows.
     if (!isset($rows[$project['project_type']])) {
       $rows[$project['project_type']] = array();
     }
-    $row_key = isset($project['title']) ? drupal_strtolower($project['title']) : drupal_strtolower($project['name']);
-    $rows[$project['project_type']][$row_key] = array(
-      'class' => array($class),
-      'data' => array($row),
-    );
+    $row_key = !empty($project['title']) ? drupal_strtolower($project['title']) : drupal_strtolower($project['name']);
+    $rows[$project['project_type']][$row_key] = $row;
   }
 
   $project_types = array(
@@ -240,15 +318,17 @@ function theme_update_report($variables) {
     'module-disabled' => t('Disabled modules'),
     'theme-disabled' => t('Disabled themes'),
   );
+  $variables['project_types'] = array();
   foreach ($project_types as $type_name => $type_label) {
     if (!empty($rows[$type_name])) {
       ksort($rows[$type_name]);
-      $output .= "\n<h3>" . $type_label . "</h3>\n";
-      $output .= theme('table', array('header' => $header, 'rows' => $rows[$type_name], 'attributes' => array('class' => array('update'))));
+      $variables['project_types'][] = array(
+        'label' => $type_label,
+        'projects' => $rows[$type_name],
+      );
     }
   }
   drupal_add_css(drupal_get_path('module', 'update') . '/update.css');
-  return $output;
 }
 
 /**
@@ -259,30 +339,37 @@ function theme_update_report($variables) {
  *   - status: The integer code for a project's current update status.
  *
  * @see update_calculate_project_data()
- * @ingroup themeable
  */
-function theme_update_status_label($variables) {
+function template_preprocess_update_status_label(&$variables) {
+  $variables['attributes'] = new Attribute(array('class' => array()));
   switch ($variables['status']) {
     case UPDATE_NOT_SECURE:
-      return '<span class="security-error">' . t('Security update required!') . '</span>';
-
+      $variables['attributes']['class'] = 'security-error';
+      $variables['text'] = 'Security update required!';
+      break;
     case UPDATE_REVOKED:
-      return '<span class="revoked">' . t('Revoked!') . '</span>';
-
+      $variables['attributes']['class'] = 'revoked';
+      $variables['text'] = 'Revoked!';
+      break;
     case UPDATE_NOT_SUPPORTED:
-      return '<span class="not-supported">' . t('Not supported!') . '</span>';
-
+      $variables['attributes']['class'] = 'not-supported';
+      $variables['text'] = 'Not supported!';
+      break;
     case UPDATE_NOT_CURRENT:
-      return '<span class="not-current">' . t('Update available') . '</span>';
-
+      $variables['attributes']['class'] = 'not-current';
+      $variables['text'] = 'Update available';
+      break;
     case UPDATE_CURRENT:
-      return '<span class="current">' . t('Up to date') . '</span>';
-
+      $variables['attributes']['class'] = 'current';
+      $variables['text'] = 'Up to date';
+      break;
   }
 }
 
 /**
- * Returns HTML for the version display of a project.
+ * Prepare variables for the version display of a project.
+ *
+ * Default template: update-version.html.twig.
  *
  * @param array $variables
  *   An associative array containing:
@@ -292,36 +379,33 @@ function theme_update_status_label($variables) {
  *     - date: The date of the release.
  *     - download_link: The URL for the downloadable file.
  *   - tag: The title of the project.
- *   - class: A string containing extra classes for the wrapping table.
- *
- * @ingroup themeable
+ *   - class: A array containing extra classes for the wrapping table.
  */
-function theme_update_version($variables) {
+function template_preprocess_update_version(&$variables) {
   $version = $variables['version'];
-  $tag = $variables['tag'];
-  $class = implode(' ', $variables['class']);
-
-  $output = '';
-  $output .= '<table class="version ' . $class . '">';
-  $output .= '<tr>';
-  $output .= '<td class="version-title">' . $tag . "</td>\n";
-  $output .= '<td class="version-details">';
-  $output .= l($version['version'], $version['release_link']);
-  $output .= ' <span class="version-date">(' . format_date($version['date'], 'custom', 'Y-M-d') . ')</span>';
-  $output .= "</td>\n";
-  $output .= '<td class="version-links">';
+
+  // Remove 'update_version' from the attributes array. This is added through
+  // template_preprocess() but we do not need it.
+  // @todo Remove after http://drupal.org/node/1938430 is resolved.
+  $attributes = array();
+  $attributes['class'] = $variables['class'];
+  $attributes['class'][] = 'version';
+  $variables['attributes'] = new Attribute($attributes);
+
+  $variables['version_link'] = l($version['version'], $version['release_link']);
+  $variables['version_date'] = format_date($version['date'], 'custom', 'Y-M-d');
+
   $links = array();
-  $links['update-download'] = array(
+  $links['download'] = array(
     'title' => t('Download'),
     'href' => $version['download_link'],
   );
-  $links['update-release-notes'] = array(
+  $links['release-notes'] = array(
     'title' => t('Release notes'),
     'href' => $version['release_link'],
   );
-  $output .= theme('links__update_version', array('links' => $links));
-  $output .= '</td>';
-  $output .= '</tr>';
-  $output .= "</table>\n";
-  return $output;
+  $variables['version_links'] = array(
+    '#theme' => 'links__update_version',
+    '#links' => $links,
+  );
 }