diff --git a/core/modules/rdf/rdf.module b/core/modules/rdf/rdf.module
index a2f74a3..8bd0be3 100644
--- a/core/modules/rdf/rdf.module
+++ b/core/modules/rdf/rdf.module
@@ -675,29 +675,22 @@ function rdf_preprocess_username(&$variables) {
     $variables['attributes']['about'] = url('user/' . $variables['uid']);
   }
 
-  $attributes = array();
   // The typeof attribute specifies the RDF type(s) of this resource. They
   // are defined in the 'rdftype' property of the user RDF mapping.
   if (!empty($rdf_mapping['rdftype'])) {
-    $attributes['typeof'] = $rdf_mapping['rdftype'];
+    $variables['attributes']['typeof'] = $rdf_mapping['rdftype'];
   }
   // Annotate the username in RDFa. A property attribute is used with an empty
   // datatype attribute to ensure the username is parsed as a plain literal
   // in RDFa 1.0 and 1.1.
   if (!empty($rdf_mapping['name'])) {
-    $attributes['property'] = $rdf_mapping['name']['predicates'];
-    $attributes['datatype'] = '';
+    $variables['attributes']['property'] = $rdf_mapping['name']['predicates'];
+    $variables['attributes']['datatype'] = '';
   }
   // Add the homepage RDFa markup if present.
   if (!empty($variables['homepage']) && !empty($rdf_mapping['homepage'])) {
-    $attributes['rel'] = $rdf_mapping['homepage']['predicates'];
-  }
-  // The remaining attributes can have multiple values listed, with whitespace
-  // separating the values in the RDFa attributes
-  // (see http://www.w3.org/TR/rdfa-syntax/#rdfa-attributes).
-  // Therefore, merge rather than override so as not to clobber values set by
-  // earlier preprocess functions.
-  $variables['attributes'] = NestedArray::mergeDeep($variables['attributes'], $attributes);
+    $variables['attributes']['rel'] = $rdf_mapping['homepage']['predicates'];
+  }
 }
 
 /**
diff --git a/core/modules/user/templates/user-picture.tpl.php b/core/modules/user/templates/user-picture.tpl.php
deleted file mode 100644
index ee82187..0000000
--- a/core/modules/user/templates/user-picture.tpl.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-/**
- * @file
- * Default theme implementation to present a picture configured for the
- * user's account.
- *
- * Available variables:
- * - $user_picture: Image set by the user or the site's default. Will be linked
- *   depending on the viewer's permission to view the user's profile page.
- * - $account: Array of account information. Potentially unsafe. Be sure to
- *   check_plain() before use.
- *
- * @see template_preprocess_user_picture()
- *
- * @ingroup themeable
- */
-?>
-<?php if ($user_picture): ?>
-  <div class="user-picture">
-    <?php print $user_picture; ?>
-  </div>
-<?php endif; ?>
diff --git a/core/modules/user/templates/user.html.twig b/core/modules/user/templates/user.html.twig
new file mode 100644
index 0000000..c89ecb4
--- /dev/null
+++ b/core/modules/user/templates/user.html.twig
@@ -0,0 +1,30 @@
+{#
+/**
+ * @file
+ * Default theme implementation to present all user data.
+ *
+ * This template is used when viewing a registered user's page,
+ * e.g., example.com/user/123. 123 being the user's ID.
+ *
+ * Available variables:
+ * - content: A list of content items. Use 'content' to print all content, or
+ *   print a subset such as 'content.field_example'.
+ * - Field variables: For each field instance attached to the user a
+ *   corresponding variable is defined; e.g., account.field_example has a
+ *   variable 'field_example' defined. When needing to access a field's raw
+ *   values, developers/themers are strongly encouraged to use these
+ *   variables. Otherwise they will have to explicitly specify the desired
+ *   field language, e.g. account.field_example.en, thus overriding any
+ *   language negotiation rule that was previously applied.
+ *
+ * @see template_preprocess()
+ * @see template_preprocess_user()
+ *
+ * @ingroup themeable
+ */
+#}
+<article{{ attributes }}>
+  {% if content is not empty %}
+    {{- content -}}
+  {% endif %}
+</article>
diff --git a/core/modules/user/templates/user.tpl.php b/core/modules/user/templates/user.tpl.php
deleted file mode 100644
index 617d310..0000000
--- a/core/modules/user/templates/user.tpl.php
+++ /dev/null
@@ -1,32 +0,0 @@
-<?php
-
-/**
- * @file
- * Default theme implementation to present all user data.
- *
- * This template is used when viewing a registered user's page,
- * e.g., example.com/user/123. 123 being the users ID.
- *
- * Use render($content) to print all content, or print a subset
- * such as render($content['field_example']).
- * By default, $user_profile['summary'] is provided, which contains data on the
- * user's history. Other data can be included by modules.
- *
- * Available variables:
- *   - $content: An array of content items. Use render() to print them.
- *   - Field variables: for each field instance attached to the user a
- *     corresponding variable is defined; e.g., $account->field_example has a
- *     variable $field_example defined. When needing to access a field's raw
- *     values, developers/themers are strongly encouraged to use these
- *     variables. Otherwise they will have to explicitly specify the desired
- *     field language, e.g. $account->field_example['en'], thus overriding any
- *     language negotiation rule that was previously applied.
- *
- * @see template_preprocess_user()
- *
- * @ingroup themeable
- */
-?>
-<article class="profile"<?php print $attributes; ?>>
-  <?php print render($content); ?>
-</article>
diff --git a/core/modules/user/user.module b/core/modules/user/user.module
index 5afcfd9..a8de3a8 100644
--- a/core/modules/user/user.module
+++ b/core/modules/user/user.module
@@ -93,8 +93,8 @@ function user_theme() {
   return array(
     'user' => array(
       'render element' => 'elements',
-      'template' => 'user',
       'file' => 'user.pages.inc',
+      'template' => 'user',
     ),
     'user_admin_permissions' => array(
       'render element' => 'form',
diff --git a/core/modules/user/user.pages.inc b/core/modules/user/user.pages.inc
index 5f0cfab..84a4d6e 100644
--- a/core/modules/user/user.pages.inc
+++ b/core/modules/user/user.pages.inc
@@ -5,6 +5,7 @@
  * User page callback file for the user module.
  */
 
+use Drupal\Core\Template\Attribute;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RedirectResponse;
@@ -179,12 +180,14 @@ function user_logout() {
 }
 
 /**
- * Process variables for user.tpl.php.
+ * Prepares variables for user templates.
  *
- * The $variables array contains the following arguments:
- * - $account
+ * Default template: user.html.twig.
  *
- * @see user.tpl.php
+ * @param array $variables
+ *   An associative array containing:
+ *   - account: The user account to check access for
+ *     (Drupal\user\Plugin\Core\Entity\User).
  */
 function template_preprocess_user(&$variables) {
   $account = $variables['elements']['#user'];
@@ -196,6 +199,9 @@ function template_preprocess_user(&$variables) {
 
   // Preprocess fields.
   field_attach_preprocess($account, $variables['elements'], $variables);
+
+  // Set up attributes.
+  $variables['attributes'] = new Attribute(array('class' => array('profile')));
 }
 
 /**