diff --git a/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
index 25222b7897600b0568bf01be511bee9f3cdec350..2dc8ed6760033213a92d67c0db3ee903ee760072 100644
--- a/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
+++ b/core/modules/link/src/Plugin/Field/FieldWidget/LinkWidget.php
@@ -257,6 +257,29 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
       // title of the 'uri' element.
       if ($this->getFieldSetting('title') == DRUPAL_DISABLED) {
         $element['uri']['#title'] = $element['#title'];
+        // By default the field description is added to the title field. Since
+        // the title field is disabled, we add the description, if given, to the
+        // uri element instead.
+        if (!empty($element['#description'])) {
+          if (empty($element['uri']['#description'])) {
+            $element['uri']['#description'] = $element['#description'];
+          }
+          else {
+            // If we have the description of the type of field together with
+            // the user provided description, we want to make a distinction
+            // between "core help text" and "user entered help text". To make
+            // this distinction more clear, we put them in an unordered list.
+            $element['uri']['#description'] = [
+              '#theme' => 'item_list',
+              '#items' => [
+                // Assume the user-specified description has the most relevance,
+                // so place it first.
+                $element['#description'],
+                $element['uri']['#description'],
+              ],
+            ];
+          }
+        }
       }
       // Otherwise wrap everything in a details element.
       else {
diff --git a/core/modules/link/tests/src/Functional/LinkFieldUITest.php b/core/modules/link/tests/src/Functional/LinkFieldUITest.php
index 0da393834b7497dc1e9a43b25c28d6a2226d78ca..bd2433f903d1aa2a3936450d9ff0ca7c3220a351 100644
--- a/core/modules/link/tests/src/Functional/LinkFieldUITest.php
+++ b/core/modules/link/tests/src/Functional/LinkFieldUITest.php
@@ -2,7 +2,10 @@
 
 namespace Drupal\Tests\link\Functional;
 
-use Drupal\Component\Utility\Unicode;
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\field_ui\Tests\FieldUiTestTrait;
 use Drupal\link\LinkItemInterface;
 use Drupal\Tests\BrowserTestBase;
@@ -30,14 +33,37 @@ class LinkFieldUITest extends BrowserTestBase {
    */
   protected $adminUser;
 
+  /**
+   * A user that should see the help texts.
+   *
+   * @var \Drupal\user\Entity\User
+   */
+  protected $helpTextUser;
+
+  /**
+   * The first content type to add fields to.
+   *
+   * @var \Drupal\node\Entity\NodeType
+   */
+  protected $firstContentType;
+
+  /**
+   * The second content type to add fields to.
+   *
+   * @var \Drupal\node\Entity\NodeType
+   */
+  protected $secondContentType;
+
   /**
    * {@inheritdoc}
    */
   protected function setUp() {
     parent::setUp();
 
+    $this->firstContentType = $this->drupalCreateContentType();
+    $this->secondContentType = $this->drupalCreateContentType();
     $this->adminUser = $this->drupalCreateUser(['administer content types', 'administer node fields', 'administer node display']);
-    $this->drupalLogin($this->adminUser);
+    $this->helpTextUser = $this->drupalCreateUser(['create ' . $this->secondContentType->id() . ' content']);
     $this->drupalPlaceBlock('system_breadcrumb_block');
   }
 
@@ -45,16 +71,91 @@ protected function setUp() {
    * Tests the link field UI.
    */
   public function testFieldUI() {
-    // Add a content type.
-    $type = $this->drupalCreateContentType();
-    $type_path = 'admin/structure/types/manage/' . $type->id();
-    $add_path = 'node/add/' . $type->id();
+    foreach ($this->providerTestFieldUI() as $item) {
+      list($cardinality, $link_type, $title, $label, $field_name) = $item;
+      $this->runFieldUIItem($cardinality, $link_type, $title, $label, $field_name);
+    }
+  }
+
+  /**
+   * Provides test data for ::testFieldUI().
+   */
+  protected function providerTestFieldUI() {
+    // There are many combinations of field settings: where the description
+    // should show: variation on internal, external, both; cardinality (where
+    // the fieldset is hidden or used); and link text shown (required or
+    // optional) or disabled. There are two descriptions: field and URL help
+    // text.
+    $cardinalities = [1, 2];
+    $title_settings = [
+      DRUPAL_DISABLED,
+      DRUPAL_OPTIONAL,
+    ];
+    $link_types = [
+      LinkItemInterface::LINK_EXTERNAL,
+      LinkItemInterface::LINK_GENERIC,
+      LinkItemInterface::LINK_INTERNAL,
+    ];
+
+    // Test all variations of link types on all cardinalities.
+    foreach ($cardinalities as $cardinality) {
+      foreach ($link_types as $link_type) {
+        // Now, test this with both the title enabled and disabled.
+        foreach ($title_settings as $title_setting) {
+          // Test both empty and non-empty labels.
+          foreach ([TRUE, FALSE] as $label_provided) {
+            // Generate a unique machine name for the field so it can be
+            // identified in the test.
+            $id = implode('_', [
+              'link',
+              $cardinality,
+              $link_type,
+              $title_setting,
+              (int) $label_provided,
+            ]);
+
+            // Use a unique label that contains some HTML.
+            $label = '<img src="http://example.com">' . $id;
+
+            yield [
+              $cardinality,
+              $link_type,
+              $title_setting,
+              $label_provided ? $label : '',
+              $id,
+            ];
+          }
+        }
+      }
+    }
+  }
+
+  /**
+   * Tests one link field UI item.
+   *
+   * @param int $cardinality
+   *   The field cardinality.
+   * @param int $link_type
+   *   Determine if the link is external, internal or both.
+   * @param int $title
+   *   Determine if the field will display the link text field.
+   * @param string $label
+   *   The field label.
+   * @param string $field_name
+   *   The unique machine name for the field.
+   */
+  public function runFieldUIItem($cardinality, $link_type, $title, $label, $field_name) {
+    $this->drupalLogin($this->adminUser);
+    $type_path = 'admin/structure/types/manage/' . $this->firstContentType->id();
 
     // Add a link field to the newly-created type. It defaults to allowing both
     // internal and external links.
-    $label = $this->randomMachineName();
-    $field_name = Unicode::strtolower($label);
-    $this->fieldUIAddNewField($type_path, $field_name, $label, 'link');
+    $field_label = str_replace('_', ' ', $field_name);
+    $description = 'link field description';
+    $field_edit = [
+      'description' => $description,
+    ];
+    $this->fieldUIAddNewField($type_path, $field_name, $field_label, 'link', [], $field_edit);
 
     // Load the formatter page to check that the settings summary does not
     // generate warnings.
@@ -62,31 +163,94 @@ public function testFieldUI() {
     $this->drupalGet("$type_path/display");
     $this->assertText(t('Link text trimmed to @limit characters', ['@limit' => 80]));
 
-    // Test the help text displays when the link field allows both internal and
-    // external links.
-    $this->drupalLogin($this->drupalCreateUser(['create ' . $type->id() . ' content']));
-    $this->drupalGet($add_path);
-    $this->assertRaw('You can also enter an internal path such as <em class="placeholder">/node/add</em> or an external URL such as <em class="placeholder">http://example.com</em>.');
+    $storage = FieldStorageConfig::create([
+      'field_name' => $field_name,
+      'entity_type' => 'node',
+      'type' => 'link',
+      'cardinality' => $cardinality,
+    ]);
+    $storage->save();
 
-    // Log in an admin to set up the next content type.
-    $this->drupalLogin($this->adminUser);
+    FieldConfig::create([
+      'field_storage' => $storage,
+      'label' => $label,
+      'bundle' => $this->secondContentType->id(),
+      'settings' => [
+        'title' => $title,
+        'link_type' => $link_type,
+      ],
+    ])->save();
 
-    // Add a different content type.
-    $type = $this->drupalCreateContentType();
-    $type_path = 'admin/structure/types/manage/' . $type->id();
-    $add_path = 'node/add/' . $type->id();
+    // Make the fields visible in the form display.
+    $form_display_id = implode('.', ['node', $this->secondContentType->id(), 'default']);
+    $form_display = EntityFormDisplay::load($form_display_id);
+    $form_display->setComponent($field_name, ['region' => 'content']);
+    $form_display->save();
 
-    // Add a link field to the newly-created type. Specify it must allow
-    // external only links.
-    $label = $this->randomMachineName();
-    $field_name = Unicode::strtolower($label);
-    $field_edit = ['settings[link_type]' => LinkItemInterface::LINK_EXTERNAL];
-    $this->fieldUIAddNewField($type_path, $field_name, $label, 'link', [], $field_edit);
+    // Log in a user that is allowed to create this content type, see if
+    // the user can see the expected help text.
+    $this->drupalLogin($this->helpTextUser);
 
-    // Test the help text displays when link allows only external links.
-    $this->drupalLogin($this->drupalCreateUser(['create ' . $type->id() . ' content']));
+    $add_path = 'node/add/' . $this->secondContentType->id();
     $this->drupalGet($add_path);
-    $this->assertRaw('This must be an external URL such as <em class="placeholder">http://example.com</em>.');
+
+    $expected_help_texts = [
+      LinkItemInterface::LINK_EXTERNAL => 'This must be an external URL such as <em class="placeholder">http://example.com</em>.',
+      LinkItemInterface::LINK_GENERIC => 'You can also enter an internal path such as <em class="placeholder">/node/add</em> or an external URL such as <em class="placeholder">http://example.com</em>. Enter <em class="placeholder">&lt;front&gt;</em> to link to the front page.',
+      LinkItemInterface::LINK_INTERNAL => rtrim(\Drupal::url('<front>', [], ['absolute' => TRUE]), '/'),
+    ];
+
+    // Check that the help texts we assume should be there, is there.
+    $this->assertFieldContainsRawText($field_name, $expected_help_texts[$link_type]);
+    if ($link_type === LinkItemInterface::LINK_INTERNAL) {
+      // Internal links have no "system" description. Test that none
+      // of the other help texts show here.
+      $this->assertNoFieldContainsRawText($field_name, $expected_help_texts[LinkItemInterface::LINK_EXTERNAL]);
+      $this->assertNoFieldContainsRawText($field_name, $expected_help_texts[LinkItemInterface::LINK_GENERIC]);
+    }
+    // Also assert that the description we made is here, no matter what the
+    // cardinality or link setting.
+    if (!empty($label)) {
+      $this->assertFieldContainsRawText($field_name, $label);
+    }
+  }
+
+  /**
+   * Checks that given field contains the given raw text.
+   *
+   * @param string $field_name
+   *   The name of the field to check.
+   * @param string $text
+   *   The text to check.
+   */
+  protected function assertFieldContainsRawText($field_name, $text) {
+    $this->assertTrue((bool) preg_match('/' . preg_quote($text, '/') . '/ui', $this->getFieldHtml($field_name)));
+  }
+
+  /**
+   * Checks that given field does not contain the given raw text.
+   *
+   * @param string $field_name
+   *   The name of the field to check.
+   * @param string $text
+   *   The text to check.
+   */
+  protected function assertNoFieldContainsRawText($field_name, $text) {
+    $this->assertFalse((bool) preg_match('/' . preg_quote($text, '/') . '/ui', $this->getFieldHtml($field_name)));
+  }
+
+  /**
+   * Returns the raw HTML for the given field.
+   *
+   * @param $field_name
+   *   The name of the field for which to return the HTML.
+   *
+   * @return string
+   *   The raw HTML.
+   */
+  protected function getFieldHtml($field_name) {
+    $css_id = Html::cleanCssIdentifier('edit-' . $field_name . '-wrapper');
+    return $this->xpath('//*[@id=:id]', [':id' => $css_id])[0]->getHtml();
   }
 
 }
diff --git a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
index 464b86c3972d4d66cbcc770b9cd5d23e7a297119..8796bc7488751282e87b206abd0f649dc73cfb54 100644
--- a/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
+++ b/core/modules/menu_link_content/tests/src/Functional/MenuLinkContentFormTest.php
@@ -78,6 +78,8 @@ public function testMenuLinkContentForm() {
     $element = $this->xpath('//select[@id = :id]/option[@selected]', [':id' => 'edit-menu-parent']);
     $this->assertTrue($element, 'A default menu parent was found.');
     $this->assertEqual('admin:', $element[0]->getValue(), '<Administration> menu is the parent.');
+    // Test that the field description is present.
+    $this->assertRaw('The location this menu link points to.');
 
     $this->drupalPostForm(
       NULL,
diff --git a/core/modules/shortcut/tests/src/Functional/ShortcutLinksTest.php b/core/modules/shortcut/tests/src/Functional/ShortcutLinksTest.php
index e39f652e55e0d4ea3b28df9628067395c1bb0bbb..77e88959b970b618372a4f7c5c8000f4d4f11ee5 100644
--- a/core/modules/shortcut/tests/src/Functional/ShortcutLinksTest.php
+++ b/core/modules/shortcut/tests/src/Functional/ShortcutLinksTest.php
@@ -65,6 +65,11 @@ public function testShortcutLinkAdd() {
       '/admin/config/system/site-information',
     ];
 
+    // Test the add shortcut form UI. Test that the base field description is
+    // there.
+    $this->drupalGet('admin/config/user-interface/shortcut/manage/' . $set->id() . '/add-link');
+    $this->assertRaw('The location this shortcut points to.');
+
     // Check that each new shortcut links where it should.
     foreach ($test_cases as $test_path) {
       $title = $this->randomMachineName();