diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index bfd1aaf..acf6935 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -1373,9 +1373,14 @@ function theme_image($variables) {
   $attributes['src'] = file_create_url($variables['uri']);
 
   foreach (array('width', 'height', 'alt', 'title') as $key) {
+    // If there is a value for the variable, it overrides the attribute.
     if (isset($variables[$key])) {
       $attributes[$key] = $variables[$key];
     }
+    // Otherwise, remove the attribute.
+    else {
+      unset($attributes[$key]);
+    }
   }
 
   return '<img' . new Attribute($attributes) . ' />';
diff --git a/core/modules/book/config/node.type.book.yml b/core/modules/book/config/node.type.book.yml
index 63f98b2..4ab1ca0 100644
--- a/core/modules/book/config/node.type.book.yml
+++ b/core/modules/book/config/node.type.book.yml
@@ -2,7 +2,7 @@ type: book
 uuid: c5ca890d-7db7-4c45-bf0f-0a12430923ff
 name: 'Book page'
 description: '<em>Books</em> have a built-in hierarchical navigation. Use for handbooks or tutorials.'
-help: ''
+help: 'Add content here organized in a hierarchy.'
 has_title: true
 title_label: Title
 settings:
diff --git a/core/modules/node/lib/Drupal/node/NodeFormController.php b/core/modules/node/lib/Drupal/node/NodeFormController.php
index 1cc58a7..ef7955f 100644
--- a/core/modules/node/lib/Drupal/node/NodeFormController.php
+++ b/core/modules/node/lib/Drupal/node/NodeFormController.php
@@ -84,6 +84,9 @@ public function form(array $form, array &$form_state) {
     // name in 'TYPE-node-form' potentially clashes with third-party class
     // names.
     $form['#attributes']['class'][0] = drupal_html_class('node-' . $node->getType() . '-form');
+    if (isset($form['help'])) {
+      $form['#attributes']['aria-describedby'] = 'block-bartik-help';
+    }
 
     // Basic node information.
     // These elements are just values so they are not even sent to the client.
diff --git a/core/profiles/standard/config/node.type.article.yml b/core/profiles/standard/config/node.type.article.yml
index a3e10b2..fe3f00f 100644
--- a/core/profiles/standard/config/node.type.article.yml
+++ b/core/profiles/standard/config/node.type.article.yml
@@ -2,7 +2,7 @@ type: article
 uuid: 38fcdfbf-92a0-43d3-af30-8395cba668d4
 name: Article
 description: 'Use <em>articles</em> for time-sensitive content like news, press releases or blog posts.'
-help: ''
+help: 'Add time-sensitive content here.'
 has_title: '1'
 title_label: Title
 settings:
diff --git a/core/profiles/standard/config/node.type.page.yml b/core/profiles/standard/config/node.type.page.yml
index d41ae94..bdfb7b7 100644
--- a/core/profiles/standard/config/node.type.page.yml
+++ b/core/profiles/standard/config/node.type.page.yml
@@ -2,7 +2,7 @@ type: page
 uuid: f77b56af-2b34-4a2f-b7e9-2dcadfdc80d0
 name: 'Basic page'
 description: 'Use <em>basic pages</em> for your static content, such as an ''About us'' page.'
-help: ''
+help: 'Add static content here.'
 has_title: '1'
 title_label: Title
 settings: