--- a/accessible/tests/mochitest/events/a11y.ini
+++ b/accessible/tests/mochitest/events/a11y.ini
@@ -3,28 +3,30 @@ support-files =
   docload_wnd.html
   focus.html
   scroll.html
   !/accessible/tests/mochitest/*.js
   !/accessible/tests/mochitest/letters.gif
 
 [test_aria_alert.html]
 [test_aria_menu.html]
+skip-if = stylo # bug 1390409
 [test_aria_objattr.html]
 [test_aria_owns.html]
 [test_aria_statechange.html]
 [test_attrs.html]
 [test_bug1322593.html]
 [test_bug1322593-2.html]
 [test_caretmove.html]
 [test_caretmove.xul]
 [test_coalescence.html]
 [test_contextmenu.html]
 [test_descrchange.html]
 [test_docload.html]
+skip-if = stylo # bug 1390409
 [test_docload_aria.html]
 [test_dragndrop.html]
 [test_flush.html]
 [test_focus_aria_activedescendant.html]
 [test_focus_autocomplete.xul]
 # Disabled on Linux and Windows due to frequent failures - bug 695019, bug 890795
 skip-if = os == 'win' || os == 'linux'
 [test_focus_canvas.html]
@@ -38,16 +40,17 @@ skip-if = os == 'win' || os == 'linux'
 [test_focus_name.html]
 [test_focus_selects.html]
 [test_focus_tabbox.xul]
 [test_focus_tree.xul]
 [test_fromUserInput.html]
 [test_label.xul]
 [test_menu.xul]
 [test_mutation.html]
+skip-if = stylo # bug 1390409
 [test_mutation.xhtml]
 [test_namechange.xul]
 [test_namechange.html]
 [test_scroll.xul]
 [test_scroll_caret.xul]
 [test_selection.html]
 skip-if = buildapp == 'mulet' || os == 'mac'
 [test_selection.xul]

--- a/accessible/tests/mochitest/treeupdate/a11y.ini
+++ b/accessible/tests/mochitest/treeupdate/a11y.ini
@@ -34,9 +34,10 @@ skip-if = buildapp == "mulet"
 [test_menubutton.xul]
 [test_optgroup.html]
 [test_recreation.html]
 [test_select.html]
 [test_shutdown.xul]
 [test_table.html]
 [test_textleaf.html]
 [test_visibility.html]
+skip-if = stylo # bug 1390409
 [test_whitespace.html]

--- a/taskcluster/ci/test/test-sets.yml
+++ b/taskcluster/ci/test/test-sets.yml
@@ -82,16 +82,17 @@ awsy-stylo-sequential:
 stylo-tests:
     - cppunit
     - crashtest
     - reftest
     - reftest-stylo
     - web-platform-tests
     - web-platform-tests-reftests
     - mochitest
+    - mochitest-a11y
     - mochitest-browser-screenshots
     - mochitest-chrome
     - mochitest-clipboard
     - mochitest-gpu
     - mochitest-media
     - mochitest-webgl
 
 stylo-sequential-tests:

--- a/taskcluster/ci/test/tests.yml
+++ b/taskcluster/ci/test/tests.yml
@@ -488,16 +488,20 @@ mochitest-a11y:
     description: "Mochitest a11y run"
     suite: mochitest/a11y
     treeherder-symbol: tc-M(a11y)
     loopback-video: true
     e10s: false
     run-on-projects:
         by-test-platform:
             linux64-qr/.*: ['mozilla-central', 'try']
+            linux64-stylo.*: ['autoland', 'mozilla-central', 'try']
+            linux64-stylo/debug: ['try']
+            macosx64-stylo/.*: ['mozilla-central', 'try']
+            windows7-32-stylo.*: ['autoland', 'mozilla-central', 'try']
             default: built-projects
     mozharness:
         script: desktop_unittest.py
         no-read-buildbot-config: true
         chunked: false
         mochitest-flavor: a11y
         config:
             by-test-platform:
@@ -505,16 +509,21 @@ mochitest-a11y:
                     - unittests/win_taskcluster_unittest.py
                 macosx.*:
                     - unittests/mac_unittest.py
                 linux.*:
                     - unittests/linux_unittest.py
                     - remove_executables.py
         extra-options:
             - --mochitest-suite=a11y
+    tier:
+        by-test-platform:
+            .*-stylo.*: 2
+            linux64-stylo/debug: 3
+            default: default
 
 mochitest-browser-chrome:
     description: "Mochitest browser-chrome run"
     suite:
         by-test-platform:
             linux64-jsdcov/opt: mochitest/browser-chrome-coverage
             default: mochitest/browser-chrome-chunked
     treeherder-symbol: tc-M(bc)