--- a/browser/components/places/content/controller.js
+++ b/browser/components/places/content/controller.js
@@ -885,20 +885,20 @@ PlacesController.prototype = {
       if (PlacesUtils.nodeIsTagQuery(node.parent)) {
         // This is a uri node inside a tag container.  It needs a special
         // untag transaction.
         var tagItemId = PlacesUtils.getConcreteItemId(node.parent);
         var uri = NetUtil.newURI(node.uri);
         if (PlacesUIUtils.useAsyncTransactions) {
           let tag = node.parent.title;
           if (!tag) {
-            let tagGuid = PlacesUtils.getConcreteItemGuid(node.parent);
+            let tagGuid = await PlacesUtils.promiseItemGuid(tagItemId);
             tag = (await PlacesUtils.bookmarks.fetch(tagGuid)).title;
           }
-          transactions.push(PlacesTransactions.Untag({ uri, tag }));
+          transactions.push(PlacesTransactions.Untag({ urls: [uri], tag }));
         } else {
           let txn = new PlacesUntagURITransaction(uri, [tagItemId]);
           transactions.push(txn);
         }
       } else if (PlacesUtils.nodeIsTagQuery(node) && node.parent &&
                PlacesUtils.nodeIsQuery(node.parent) &&
                PlacesUtils.asQuery(node.parent).queryOptions.resultType ==
                  Ci.nsINavHistoryQueryOptions.RESULTS_AS_TAG_QUERY) {

--- a/browser/components/places/tests/browser/browser.ini
+++ b/browser/components/places/tests/browser/browser.ini
@@ -33,16 +33,17 @@ subsuite = clipboard
 [browser_copy_folder_tree.js]
 [browser_copy_query_without_tree.js]
 subsuite = clipboard
 [browser_drag_bookmarks_on_toolbar.js]
 [browser_forgetthissite_single.js]
 [browser_history_sidebar_search.js]
 [browser_library_batch_delete.js]
 [browser_library_commands.js]
+[browser_library_delete_bookmarks_in_tags.js]
 [browser_library_delete_tags.js]
 [browser_library_downloads.js]
 [browser_library_infoBox.js]
 [browser_library_left_pane_fixnames.js]
 [browser_library_left_pane_middleclick.js]
 [browser_library_left_pane_select_hierarchy.js]
 [browser_library_middleclick.js]
 [browser_library_move_bookmarks.js]

new file mode 100644
--- /dev/null
+++ b/browser/components/places/tests/browser/browser_library_delete_bookmarks_in_tags.js
@@ -0,0 +1,96 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ *  Test deleting bookmarks from within tags.
+ */
+
+registerCleanupFunction(async function() {
+  await PlacesUtils.bookmarks.eraseEverything();
+  await PlacesTestUtils.clearHistory();
+});
+
+add_task(async function test_tags() {
+  const uris = [
+    Services.io.newURI("http://example.com/1"),
+    Services.io.newURI("http://example.com/2"),
+    Services.io.newURI("http://example.com/3"),
+  ];
+
+  let children = uris.map((uri, index, arr) => {
+    return {
+      title: `bm${index}`,
+      url: uri,
+    }
+  })
+
+  // Note: we insert the uris in reverse order, so that we end up with the
+  // display in "logical" order of bm0 at the top, and bm2 at the bottom.
+  children = children.reverse();
+
+  await PlacesUtils.bookmarks.insertTree({
+    guid: PlacesUtils.bookmarks.unfiledGuid,
+    children,
+  });
+
+  for (let i = 0; i < uris.length; i++) {
+    PlacesUtils.tagging.tagURI(uris[i], ["test"]);
+  }
+
+  let library = await promiseLibrary();
+
+  // Select and open the left pane "Bookmarks Toolbar" folder.
+  let PO = library.PlacesOrganizer;
+
+  PO.selectLeftPaneQuery("Tags");
+  let tagsNode = PO._places.selectedNode;
+  Assert.notEqual(tagsNode, null, "Should have a valid selection");
+  let tagsTitle = PlacesUtils.getString("TagsFolderTitle");
+  Assert.equal(tagsNode.title, tagsTitle,
+               "Should have selected the Tags node");
+
+  // Now select the tag.
+  PlacesUtils.asContainer(tagsNode).containerOpen = true;
+  let tag = tagsNode.getChild(0);
+  PO._places.selectNode(tag);
+  Assert.equal(PO._places.selectedNode.title, "test",
+               "Should have selected the created tag");
+
+  let ContentTree = library.ContentTree;
+
+  for (let i = 0; i < uris.length; i++) {
+    ContentTree.view.selectNode(ContentTree.view.result.root.getChild(0));
+
+    Assert.equal(ContentTree.view.selectedNode.title, `bm${i}`,
+                 `Should have selected bm${i}`);
+
+    let promiseNotification = PlacesTestUtils.waitForNotification("onItemChanged",
+      (id, property) => property == "tags");
+
+    ContentTree.view.controller.doCommand("cmd_delete");
+
+    await promiseNotification;
+
+    for (let j = 0; j < uris.length; j++) {
+      let tags = PlacesUtils.tagging.getTagsForURI(uris[j]);
+      if (j <= i) {
+        Assert.equal(tags.length, 0,
+                     `There should be no tags for the URI: ${uris[j].spec}`);
+      } else {
+        Assert.equal(tags.length, 1,
+                     `There should be one tag for the URI: ${uris[j].spec}`);
+      }
+    }
+  }
+
+  // The tag should now not exist.
+  Assert.deepEqual(PlacesUtils.tagging.getURIsForTag("test"), [],
+                   "There should be no URIs remaining for the tag");
+
+  tagsNode.containerOpen = false;
+
+  library.close();
+});