--- a/testing/mozharness/configs/unittests/linux_unittest.py
+++ b/testing/mozharness/configs/unittests/linux_unittest.py
@@ -269,23 +269,23 @@ config = {
                         "--setpref=browser.tabs.remote.autostart=true",
                         "--setpref=layers.async-pan-zoom.enabled=true"],
             "tests": ["tests/reftest/tests/testing/crashtest/crashtests.list"]
         },
     },
     "all_xpcshell_suites": {
         "xpcshell": {
             "options": ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             "tests": []
         },
         "xpcshell-addons": {
             "options": ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
                         "--tag=addons",
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             "tests": []
         },
     },
     "all_cppunittest_suites": {
         "cppunittest": {"tests": ["tests/cppunittest"]}
     },
     "all_gtest_suites": {
         "gtest": []

--- a/testing/mozharness/configs/unittests/mac_unittest.py
+++ b/testing/mozharness/configs/unittests/mac_unittest.py
@@ -204,23 +204,23 @@ config = {
                         '--setpref=browser.tabs.remote.autostart=true',
                         '--setpref=layers.async-pan-zoom.enabled=true'],
             'tests': ['tests/reftest/tests/testing/crashtest/crashtests.list']
         },
     },
     "all_xpcshell_suites": {
         "xpcshell": {
             'options': ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             'tests': []
         },
         "xpcshell-addons": {
             'options': ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
                         "--tag=addons",
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             'tests': []
         },
     },
     "all_cppunittest_suites": {
         "cppunittest": ['tests/cppunittest']
     },
     "all_gtest_suites": {
         "gtest": []

--- a/testing/mozharness/configs/unittests/win_unittest.py
+++ b/testing/mozharness/configs/unittests/win_unittest.py
@@ -227,23 +227,23 @@ config = {
                         '--setpref=browser.tabs.remote.autostart=true',
                         '--setpref=layers.async-pan-zoom.enabled=true'],
             "tests": ['tests/reftest/tests/testing/crashtest/crashtests.list'],
         },
     },
     "all_xpcshell_suites": {
         "xpcshell": {
             'options': ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             'tests': []
         },
         "xpcshell-addons": {
             'options': ["--xpcshell=%(abs_app_dir)s/" + XPCSHELL_NAME,
                         "--tag=addons",
-                        "--manifest=tests/xpcshell/tests/all-test-dirs.list"],
+                        "--manifest=tests/xpcshell/tests/xpcshell.ini"],
             'tests': []
         },
     },
     "all_cppunittest_suites": {
         "cppunittest": ['tests/cppunittest']
     },
     "all_gtest_suites": {
         "gtest": []

deleted file mode 100644
--- a/testing/xpcshell/Makefile.in
+++ /dev/null
@@ -1,9 +0,0 @@
-#
-# 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/.
-
-include $(topsrcdir)/config/rules.mk
-
-libs::
-	cp $(DEPTH)/_tests/xpcshell/xpcshell.ini $(DEPTH)/_tests/xpcshell/all-test-dirs.list