diff --git a/core/modules/comment/comment.admin.inc b/core/modules/comment/comment.admin.inc
index 99bb6b0..abbf800 100644
--- a/core/modules/comment/comment.admin.inc
+++ b/core/modules/comment/comment.admin.inc
@@ -41,7 +41,6 @@ function comment_admin($type = 'new') {
  * @see comment_admin()
  * @see comment_admin_overview_validate()
  * @see comment_admin_overview_submit()
- * @see theme_comment_admin_overview()
  */
 function comment_admin_overview($form, &$form_state, $arg) {
   // Build an 'Update options' form.
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index 3c92450..75a4cbc 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -163,19 +163,13 @@ function comment_field_extra_fields() {
  */
 function comment_theme() {
   return array(
-    'comment_preview' => array(
-      'variables' => array('comment' => NULL),
-    ),
     'comment' => array(
-      'template' => 'comment',
       'render element' => 'elements',
-    ),
-    'comment_post_forbidden' => array(
-      'variables' => array('commented_entity' => NULL, 'field_name' => 'comment'),
+      'template' => 'comment',
     ),
     'comment_wrapper' => array(
-      'template' => 'comment-wrapper',
       'render element' => 'content',
+      'template' => 'comment-wrapper',
     ),
   );
 }
@@ -494,13 +488,8 @@ function comment_entity_view(EntityInterface $entity, EntityViewDisplayInterface
             }
           }
           else {
-            $comment_post_forbidden = array(
-              '#theme' => 'comment_post_forbidden',
-              '#commented_entity' => $entity,
-              '#field_name' => $field_name,
-            );
             $links['comment-forbidden'] = array(
-              'title' => drupal_render($comment_post_forbidden),
+              'title' => comment_forbidden_message($entity, $field_name),
               'html' => TRUE,
             );
           }
@@ -529,13 +518,8 @@ function comment_entity_view(EntityInterface $entity, EntityViewDisplayInterface
             }
           }
           else {
-            $comment_post_forbidden = array(
-              '#theme' => 'comment_post_forbidden',
-              '#commented_entity' => $entity,
-              '#field_name' => $field_name,
-            );
             $links['comment-forbidden'] = array(
-              'title' => drupal_render($comment_post_forbidden),
+              'title' => comment_forbidden_message($entity, $field_name),
               'html' => TRUE,
             );
           }
@@ -1475,19 +1459,21 @@ function template_preprocess_comment(&$variables) {
 }
 
 /**
- * Returns HTML for a "you can't post comments" notice.
+ * Provides a message if posting comments is forbidden.
  *
- * @param $variables
- *   An associative array containing:
- *   - commented_entity: The entity to which comments are attached to.
- *   - field_name: The comment field.
+ * If authenticated users can post comments, a message is returned that prompts
+ * the anonymous user to log in (or register, if applicable) that redirects to
+ * entity comment form. Otherwise, no message is returned.
  *
- * @ingroup themeable
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ *   The entity to which comments are attached to.
+ * @param string $field_name
+ *   The field name on the entity to which comments are attached to.
+ *
+ * @return
+ *   HTML for a "you can't post comments" notice.
  */
-function theme_comment_post_forbidden($variables) {
-  $entity = $variables['commented_entity'];
-  $field_name = $variables['field_name'];
-
+function comment_forbidden_message(EntityInterface $entity, $field_name) {
   // Since this is expensive to compute, we cache it so that a page with many
   // comments only has to query the database once for all the links.
   $authenticated_post_comments = &drupal_static(__FUNCTION__, NULL);
diff --git a/core/modules/comment/lib/Drupal/comment/CommentViewBuilder.php b/core/modules/comment/lib/Drupal/comment/CommentViewBuilder.php
index dc4cd61..2c5de3a 100644
--- a/core/modules/comment/lib/Drupal/comment/CommentViewBuilder.php
+++ b/core/modules/comment/lib/Drupal/comment/CommentViewBuilder.php
@@ -240,12 +240,7 @@ protected static function buildLinks(CommentInterface $entity, EntityInterface $
         );
       }
       if (empty($links)) {
-        $comment_post_forbidden = array(
-          '#theme' => 'comment_post_forbidden',
-          '#commented_entity' => $commented_entity,
-          '#field_name' => $entity->field_name->value,
-        );
-        $links['comment-forbidden']['title'] = drupal_render($comment_post_forbidden);
+        $links['comment-forbidden']['title'] = comment_forbidden_message($commented_entity, $entity->field_name->value);
         $links['comment-forbidden']['html'] = TRUE;
       }
     }
diff --git a/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php b/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
index 6eabd64..9739602 100644
--- a/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
+++ b/core/modules/comment/lib/Drupal/comment/Tests/CommentLinksTest.php
@@ -260,7 +260,7 @@ function assertCommentLinks(array $info) {
 
         // Anonymous users should see a note to log in or register in case
         // authenticated users are allowed to post comments.
-        // @see theme_comment_post_forbidden()
+        // @see comment_forbidden_message()
         if (!$this->loggedInUser) {
           if (user_access('post comments', $this->web_user)) {
             // The note depends on whether users are actually able to register.