diff --git a/core/modules/node/node.preview.js b/core/modules/node/node.preview.js
index 9041f24..33383a3 100644
--- a/core/modules/node/node.preview.js
+++ b/core/modules/node/node.preview.js
@@ -8,11 +8,36 @@
    */
   Drupal.behaviors.nodePreviewDestroyLinks = {
     attach: function (context) {
+
+      function clickPreviewModal(event) {
+        // Only confirm leaving previews when left-clicking and user is not
+        // pressing the ALT, CTRL, META (Command key on the Macintosh keyboard)
+        // or SHIFT key.
+        if (event.button === 0 && !event.altKey && !event.ctrlKey && !event.metaKey && !event.shiftKey) {
+          event.preventDefault();
+          var $previewDialog = $('<dialog>' + Drupal.theme('nodePreviewModal') + '</dialog>').appendTo('body');
+          Drupal.dialog($previewDialog, {
+            title: Drupal.t('Leave preview?'),
+            buttons: [
+              {
+                text: Drupal.t('Cancel'),
+                click: function () {
+                  $(this).dialog('close');
+                }
+              }, {
+                text: Drupal.t('Leave preview'),
+                click: function () {
+                  window.top.location.href = event.target.href;
+                }
+              }
+            ]
+          }).showModal();
+        }
+      }
+
       var $preview = $(context).find('.page-node-preview').once('node-preview');
       if ($preview.length) {
-        $preview.on('click.preview', 'a:not([href^=#], #edit-backlink, #toolbar-administration a)', function (e) {
-          e.preventDefault();
-        });
+        $preview.on('click.preview', 'a:not([href^=#], #edit-backlink, #toolbar-administration a)', clickPreviewModal);
       }
     },
     detach: function (context, settings, trigger) {
@@ -32,11 +57,18 @@
     attach: function (context) {
       var $autosubmit = $(context).find('[data-drupal-autosubmit]').once('autosubmit');
       if ($autosubmit.length) {
-        $autosubmit.on('formUpdated.preview', function() {
+        $autosubmit.on('formUpdated.preview', function () {
           $(this.form).trigger('submit');
         });
       }
     }
   };
 
+  Drupal.theme.nodePreviewModal = function () {
+    return '<p>' +
+      Drupal.t('Leaving the preview will cause unsaved changes to be lost. Are you sure you want to leave the preview?') +
+      '</p><small class="description">' +
+      Drupal.t('CTRL+Left click will prevent this dialog from showing and proceed to the clicked link.') + '</small>';
+  };
+
 })(jQuery, Drupal);