--- a/taskcluster/ci/android-test/tests.yml
+++ b/taskcluster/ci/android-test/tests.yml
@@ -11,264 +11,264 @@
 
 cppunit:
     description: "CPP Unit Tests"
     suite: cppunittest
     treeherder-symbol: tc(Cpp)
     e10s: false
     loopback-video: true
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=cppunittest
 
 crashtest:
     description: "Crashtest run"
     suite: crashtest
     treeherder-symbol: tc-R(C)
     instance-size: xlarge
     chunks:
         by-test-platform:
             android-4.3-arm7-api-15/debug: 10
             default: 4
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=crashtest
 
 jsreftest:
     description: "JS Reftest run"
     suite: reftest/jsreftest
     treeherder-symbol: tc-R(J)
     instance-size: xlarge
     chunks:
         by-test-platform:
             android-4.3-arm7-api-15/debug: 20
             default: 6
     loopback-video: true
     max-run-time: 7200
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=jsreftest
 
 marionette:
     description: "Marionette unittest run"
     suite: marionette
     treeherder-symbol: tc(Mn)
     chunks: 10
     instance-size: xlarge
     loopback-video: true
     e10s: false
     tier: 3
     max-run-time: 3600
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=marionette
 
 mochitest:
     description: "Mochitest plain run"
     suite: mochitest/plain-chunked
     treeherder-symbol: tc-M()
     instance-size: xlarge
     chunks: 20
     loopback-video: true
     e10s: false
     max-run-time:
         by-test-platform:
             android-4.3-arm7-api-15/debug: 10800
             default: 3600
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest
 
 mochitest-chrome:
     description: "Mochitest chrome run"
     suite: mochitest/chrome
     treeherder-symbol: tc-M(c)
     instance-size: xlarge
     chunks:
         by-test-platform:
             android-4.3-arm7-api-15/debug: 2
             default: 1
     loopback-video: true
     e10s: false
     max-run-time: 5400
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest-chrome
 
 mochitest-clipboard:
     description: "Mochitest clipboard run"
     suite: mochitest/plain-clipboard
     treeherder-symbol: tc-M(cl)
     instance-size: xlarge
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest-plain-clipboard
 
 mochitest-gpu:
     description: "Mochitest gpu run"
     suite: mochitest/plain-gpu
     treeherder-symbol: tc-M(gpu)
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest-plain-gpu
 
 mochitest-media:
     description: "Mochitest media run"
     suite: mochitest/mochitest-media
     treeherder-symbol: tc-M(mda)
     instance-size: xlarge
     chunks: 3
     loopback-video: true
     e10s: false
     max-run-time: 5400
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest-media
 
 mochitest-webgl:
     description: "Mochitest webgl run"
     suite: mochitest/mochitest-gl
     treeherder-symbol: tc-M(gl)
     chunks: 10
     loopback-video: true
     e10s: false
     max-run-time: 7200
     instance-size: xlarge
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=mochitest-gl
 
 reftest:
     description: "Reftest run"
     suite: reftest/reftest
     treeherder-symbol: tc-R(R)
     chunks:
         by-test-platform:
             android-4.3-arm7-api-15/debug: 48
             default: 16
     instance-size: xlarge
     max-run-time: 10800
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=reftest
 
 robocop:
     description: "Robocop run"
     suite: robocop
     treeherder-symbol: tc-M(rc)
     instance-size: xlarge
     chunks:
         by-test-platform:
             # android-4.3-arm7-api-15/debug -- not run
             android-4.3-arm7-api-15/opt: 4
             android-4.3-arm7-api-15-gradle/opt: 4
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         config:
-            - android/androidarm_4_3.py
-            - remove_executables.py
-            - android/androidarm_4_3-tc.py
+            - mozharness/configs/android/androidarm_4_3.py
+            - mozharness/configs/remove_executables.py
+            - mozharness/configs/android/androidarm_4_3-tc.py
         extra-options:
             - --test-suite=robocop
 
 xpcshell:
     description: "xpcshell test run"
     suite: xpcshell
     treeherder-symbol: tc-X()
     chunks:
         by-test-platform:
             default: 3
             android-4.2-x86/opt: 4
     instance-size: xlarge
     max-run-time: 7200
     loopback-video: true
     e10s: false
     mozharness:
-        script: android_emulator_unittest.py
+        script: mozharness/scripts/android_emulator_unittest.py
         no-read-buildbot-config: true
         extra-options:
             - --test-suite=xpcshell
         config:
             by-test-platform:
                 default:
-                    - android/androidarm_4_3.py
-                    - remove_executables.py
-                    - android/androidarm_4_3-tc.py
+                    - mozharness/configs/android/androidarm_4_3.py
+                    - mozharness/configs/remove_executables.py
+                    - mozharness/configs/android/androidarm_4_3-tc.py
                 android-4.2-x86/opt:
-                    - android/androidx86-tc.py
+                    - mozharness/configs/android/androidx86-tc.py

--- a/taskcluster/ci/build/windows.yml
+++ b/taskcluster/ci/build/windows.yml
@@ -9,17 +9,17 @@ win32/debug:
         symbol: tc(B)
         tier: 2
     worker-type: aws-provisioner-v1/gecko-{level}-b-win2012
     worker:
         implementation: generic-worker
         max-run-time: 7200
     run:
         using: mozharness
-        script: fx_desktop_build.py
+        script: mozharness/scripts/fx_desktop_build.py
         config:
             - builds/taskcluster_firefox_win32_debug.py
 
 win32/opt:
     description: "Win32 Opt"
     index:
         product: firefox
         job-name:
@@ -29,17 +29,17 @@ win32/opt:
         symbol: tc(B)
         tier: 2
     worker-type: aws-provisioner-v1/gecko-{level}-b-win2012
     worker:
         implementation: generic-worker
         max-run-time: 7200
     run:
         using: mozharness
-        script: fx_desktop_build.py
+        script: mozharness/scripts/fx_desktop_build.py
         config:
             - builds/taskcluster_firefox_win32_opt.py
 
 win64/debug:
     description: "Win64 Debug"
     index:
         product: firefox
         job-name:
@@ -49,17 +49,17 @@ win64/debug:
         symbol: tc(B)
         tier: 2
     worker-type: aws-provisioner-v1/gecko-{level}-b-win2012
     worker:
         implementation: generic-worker
         max-run-time: 7200
     run:
         using: mozharness
-        script: fx_desktop_build.py
+        script: mozharness/scripts/fx_desktop_build.py
         config:
             - builds/taskcluster_firefox_win64_debug.py
 
 win64/opt:
     description: "Win64 Opt"
     index:
         product: firefox
         job-name:
@@ -69,12 +69,12 @@ win64/opt:
         symbol: tc(B)
         tier: 2
     worker-type: aws-provisioner-v1/gecko-{level}-b-win2012
     worker:
         implementation: generic-worker
         max-run-time: 7200
     run:
         using: mozharness
-        script: fx_desktop_build.py
+        script: mozharness/scripts/fx_desktop_build.py
         config:
             - builds/taskcluster_firefox_win64_opt.py
 

--- a/taskcluster/ci/desktop-test/tests.yml
+++ b/taskcluster/ci/desktop-test/tests.yml
@@ -6,441 +6,441 @@
 # Note that these are in lexical order
 
 cppunit:
     description: "CPP Unit Tests"
     suite: cppunittest
     treeherder-symbol: tc(Cpp)
     e10s: false
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 # Coming soon:
                 # win.*:
-                #    - unittests/win_unittest.py
-                #    - remove_executables.py
+                #    - mozharness/configs/unittests/win_unittest.py
+                #    - mozharness/configs/remove_executables.py
                 # ...
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --cppunittest-suite=cppunittest
 
 crashtest:
     description: "Crashtest run"
     suite: reftest/crashtest
     treeherder-symbol: tc-R(C)
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         chunked: true
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --reftest-suite=crashtest
 
 external-media-tests:
     description: "External Media Test run"
     suite: external-media-tests
     treeherder-symbol: tc-VP(b-m)
     e10s: false
     tier: 2
     max-run-time: 5400
     mozharness:
-        script: firefox_media_tests_buildbot.py
+        script: mozharness/scripts/firefox_media_tests_buildbot.py
         no-read-buildbot-config: true
         config:
-            - mediatests/buildbot_posix_config.py
-            - remove_executables.py
+            - mozharness/configs/mediatests/buildbot_posix_config.py
+            - mozharness/configs/remove_executables.py
 
 firefox-ui-functional-local:
     description: "Firefox-ui-tests functional run"
     suite: "firefox-ui/functional local"
     treeherder-symbol: tc-Fxfn-l(en-US)
     max-run-time: 5400
     tier: 1
     docker-image: {"in-tree": "desktop1604-test"}
     mozharness:
-        script: firefox_ui_tests/functional.py
+        script: mozharness/scripts/firefox_ui_tests/functional.py
         config:
-            - firefox_ui_tests/taskcluster.py
-            - remove_executables.py
+            - mozharness/configs/firefox_ui_tests/taskcluster.py
+            - mozharness/configs/remove_executables.py
         extra-options:
             - "--tag local"
 
 firefox-ui-functional-remote:
     description: "Firefox-ui-tests functional run"
     suite: "firefox-ui/functional remote"
     treeherder-symbol: tc-Fxfn-r(en-US)
     max-run-time: 5400
     tier: 2
     docker-image: {"in-tree": "desktop1604-test"}
     mozharness:
-        script: firefox_ui_tests/functional.py
+        script: mozharness/scripts/firefox_ui_tests/functional.py
         config:
-            - firefox_ui_tests/taskcluster.py
-            - remove_executables.py
+            - mozharness/configs/firefox_ui_tests/taskcluster.py
+            - mozharness/configs/remove_executables.py
         extra-options:
             - "--tag remote"
 
 gtest:
     description: "GTests run"
     suite: gtest
     treeherder-symbol: tc(GTest)
     e10s: false
     instance-size: xlarge
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --gtest-suite=gtest
 
 jittests:
     description: "JIT Test run"
     suite: jittest/jittest-chunked
     treeherder-symbol: tc(Jit)
     e10s: false
     chunks: 6
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --jittest-suite=jittest-chunked
 
 jsreftest:
     description: "JS Reftest run"
     suite: reftest/jsreftest
     treeherder-symbol: tc-R(J)
     chunks: 2
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --reftest-suite=jsreftest
 
 marionette:
     description: "Marionette unittest run"
     suite: marionette
     treeherder-symbol: tc(Mn)
     max-run-time: 5400
     mozharness:
-        script: marionette.py
+        script: mozharness/scripts/marionette.py
         no-read-buildbot-config: true
         config:
-            - marionette/prod_config.py
-            - remove_executables.py
+            - mozharness/configs/marionette/prod_config.py
+            - mozharness/configs/remove_executables.py
 
 mochitest:
     description: "Mochitest plain run"
     suite: mochitest/plain-chunked
     treeherder-symbol: tc-M()
     loopback-video: true
     chunks: 10
     max-run-time: 5400
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=plain-chunked
     # Bug 1281241: migrating to m3.large instances
     instance-size: legacy
     allow-software-gl-layers: false
 
 mochitest-a11y:
     description: "Mochitest a11y run"
     suite: mochitest/a11y
     treeherder-symbol: tc-M(a11y)
     loopback-video: true
     e10s: false
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=a11y
 
 mochitest-browser-chrome:
     description: "Mochitest browser-chrome run"
     suite: mochitest/browser-chrome-chunked
     treeherder-symbol: tc-M(bc)
     loopback-video: true
     chunks: 7
     max-run-time:
         by-test-platform:
             linux64/debug: 5400
             default: 3600
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=browser-chrome-chunked
     # Bug 1281241: migrating to m3.large instances
     instance-size: legacy
     allow-software-gl-layers: false
 
 mochitest-chrome:
     description: "Mochitest chrome run"
     suite: mochitest/chrome
     treeherder-symbol: tc-M(c)
     loopback-video: true
     chunks: 3
     e10s: false
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=chrome
 
 mochitest-clipboard:
     description: "Mochitest clipboard run"
     suite: mochitest/plain-clipboard,chrome-clipboard,browser-chrome-clipboard,jetpack-package-clipboard
     treeherder-symbol: tc-M(cl)
     loopback-video: true
     instance-size: xlarge
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=plain-clipboard,chrome-clipboard,browser-chrome-clipboard,jetpack-package-clipboard
 
 mochitest-devtools-chrome:
     description: "Mochitest devtools-chrome run"
     suite: mochitest/mochitest-devtools-chrome-chunked
     treeherder-symbol: tc-M(dt)
     loopback-video: true
     max-run-time: 5400
     chunks: 10
     e10s:
         by-test-platform:
             # Bug 1242986: linux64/debug mochitest-devtools-chrome e10s is not greened up yet
             linux64/debug: false
             default: both
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=mochitest-devtools-chrome-chunked
     instance-size:
         by-test-platform:
             # Bug 1281241: migrating to m3.large instances
             linux64-asan/opt: legacy
             default: default
     # Bug 1296086: high number of intermittents observed with software GL and large instances
     allow-software-gl-layers: false
 
 mochitest-gpu:
     description: "Mochitest GPU run"
     suite: mochitest/plain-gpu,chrome-gpu,browser-chrome-gpu
     treeherder-symbol: tc-M(gpu)
     loopback-video: true
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=plain-gpu,chrome-gpu,browser-chrome-gpu
 
 mochitest-jetpack:
     description: "Mochitest jetpack run"
     suite: mochitest/jetpack-package
     treeherder-symbol: tc-M(JP)
     loopback-video: true
     e10s: false
     max-run-time: 5400
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=jetpack-package
 
 mochitest-media:
     description: "Mochitest media run"
     suite: mochitest/mochitest-media
     treeherder-symbol: tc-M(mda)
     max-run-time: 5400
     loopback-video: true
     instance-size: large
     docker-image: {"in-tree": "desktop1604-test"}
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=mochitest-media
 
 mochitest-webgl:
     description: "Mochitest webgl run"
     suite: mochitest/mochitest-gl
     treeherder-symbol: tc-M(gl)
     chunks: 3
     loopback-video: true
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         chunked: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --mochitest-suite=mochitest-gl
     # Bug 1296733: llvmpipe with mesa 9.2.1 lacks thread safety
     allow-software-gl-layers: false
 
 reftest:
     description: "Reftest run"
     suite: reftest/reftest
     treeherder-symbol: tc-R(R)
     chunks: 8
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --reftest-suite=reftest
 
 reftest-no-accel:
     description: "Reftest not accelerated run"
     suite: reftest/reftest-no-accel
     treeherder-symbol: tc-R(Ru)
     chunks: 8
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --reftest-suite=reftest-no-accel
 
 web-platform-tests:
     description: "Web platform test run"
     suite: web-platform-tests
     treeherder-symbol: tc-W()
     chunks: 12
     max-run-time: 7200
     instance-size: xlarge
     docker-image: {"in-tree": "desktop1604-test"}
     checkout: true
     mozharness:
-        script: web_platform_tests.py
+        script: mozharness/scripts/web_platform_tests.py
         no-read-buildbot-config: true
         config:
-            - web_platform_tests/prod_config.py
-            - remove_executables.py
+            - mozharness/configs/web_platform_tests/prod_config.py
+            - mozharness/configs/remove_executables.py
         extra-options:
             - --test-type=testharness
 
 web-platform-tests-reftests:
     description: "Web platform reftest run"
     suite: web-platform-tests-reftests
     treeherder-symbol: tc-W(Wr)
     max-run-time: 5400
     instance-size: xlarge
     docker-image: {"in-tree": "desktop1604-test"}
     checkout: true
     mozharness:
-        script: web_platform_tests.py
+        script: mozharness/scripts/web_platform_tests.py
         no-read-buildbot-config: true
         config:
-            - web_platform_tests/prod_config.py
-            - remove_executables.py
+            - mozharness/configs/web_platform_tests/prod_config.py
+            - mozharness/configs/remove_executables.py
         extra-options:
             - --test-type=reftest
 
 xpcshell:
     description: "xpcshell test run"
     suite: xpcshell
     treeherder-symbol: tc-X()
     chunks:
         by-test-platform:
             linux64/debug: 10
             default: 8
     max-run-time: 5400
     e10s: false
     mozharness:
-        script: desktop_unittest.py
+        script: mozharness/scripts/desktop_unittest.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 default:
-                    - unittests/linux_unittest.py
-                    - remove_executables.py
+                    - mozharness/configs/unittests/linux_unittest.py
+                    - mozharness/configs/remove_executables.py
         extra-options:
             - --xpcshell-suite=xpcshell
     # Bug 1281241: migrating to m3.large instances
     instance-size: legacy
     allow-software-gl-layers: false

--- a/taskcluster/scripts/tester/test-ubuntu.sh
+++ b/taskcluster/scripts/tester/test-ubuntu.sh
@@ -15,17 +15,16 @@ fi
 . /home/worker/scripts/xvfb.sh
 
 ####
 # Taskcluster friendly wrapper for performing fx desktop tests via mozharness.
 ####
 
 # Inputs, with defaults
 
-: MOZHARNESS_PATH               ${MOZHARNESS_PATH}
 : MOZHARNESS_URL                ${MOZHARNESS_URL}
 : MOZHARNESS_SCRIPT             ${MOZHARNESS_SCRIPT}
 : MOZHARNESS_CONFIG             ${MOZHARNESS_CONFIG}
 : NEED_XVFB                     ${NEED_XVFB:=true}
 : NEED_WINDOW_MANAGER           ${NEED_WINDOW_MANAGER:=false}
 : NEED_PULSEAUDIO               ${NEED_PULSEAUDIO:=false}
 : START_VNC                     ${START_VNC:=false}
 : TASKCLUSTER_INTERACTIVE       ${TASKCLUSTER_INTERACTIVE:=false}
@@ -44,50 +43,43 @@ fail() {
 maybe_start_pulse() {
     if $NEED_PULSEAUDIO; then
         pulseaudio --fail --daemonize --start
         pactl load-module module-null-sink
     fi
 }
 
 # test required parameters are supplied
-if [ -z "${MOZHARNESS_PATH}" -a -z "${MOZHARNESS_URL}" ]; then
-    fail "MOZHARNESS_PATH or MOZHARNESS_URL must be defined";
-fi
-
+if [[ -z ${MOZHARNESS_URL} ]]; then fail "MOZHARNESS_URL is not set"; fi
 if [[ -z ${MOZHARNESS_SCRIPT} ]]; then fail "MOZHARNESS_SCRIPT is not set"; fi
 if [[ -z ${MOZHARNESS_CONFIG} ]]; then fail "MOZHARNESS_CONFIG is not set"; fi
 
 mkdir -p ~/artifacts/public
 
 cleanup() {
     local rv=$?
     if [[ -s /home/worker/.xsession-errors ]]; then
       # To share X issues
       cp /home/worker/.xsession-errors ~/artifacts/public/xsession-errors.log
     fi
     cleanup_xvfb
     exit $rv
 }
 trap cleanup EXIT INT
 
-# Download mozharness if we're told to.
-if [ ${MOZHARNESS_URL} ]; then
-    if ! curl --fail -o mozharness.zip --retry 10 -L $MOZHARNESS_URL; then
-        fail "failed to download mozharness zip"
-    fi
-    rm -rf mozharness
-    unzip -q mozharness.zip
-    rm mozharness.zip
+# Unzip the mozharness ZIP file created by the build task
+if ! curl --fail -o mozharness.zip --retry 10 -L $MOZHARNESS_URL; then
+    fail "failed to download mozharness zip"
+fi
+rm -rf mozharness
+unzip -q mozharness.zip
+rm mozharness.zip
 
-    if ! [ -d mozharness ]; then
-        fail "mozharness zip did not contain mozharness/"
-    fi
-
-    MOZHARNESS_PATH=`pwd`/mozharness
+if ! [ -d mozharness ]; then
+    fail "mozharness zip did not contain mozharness/"
 fi
 
 # pulseaudio daemon must be started before xvfb on Ubuntu 12.04.
 if ${UBUNTU_1204}; then
     maybe_start_pulse
 fi
 
 # run XVfb in the background, if necessary
@@ -133,28 +125,28 @@ fi
 # source it is running; tc-vcs obscures this a little, but we can provide
 # it directly.
 export MOZ_SOURCE_REPO="${GECKO_HEAD_REPOSITORY}"
 export MOZ_SOURCE_CHANGESET="${GECKO_HEAD_REV}"
 
 # support multiple, space delimited, config files
 config_cmds=""
 for cfg in $MOZHARNESS_CONFIG; do
-  config_cmds="${config_cmds} --config-file ${MOZHARNESS_PATH}/configs/${cfg}"
+  config_cmds="${config_cmds} --config-file $WORKSPACE/${cfg}"
 done
 
 mozharness_bin="/home/worker/bin/run-mozharness"
 
 # Save the computed mozharness command to a binary which is useful
 # for interactive mode.
 echo -e "#!/usr/bin/env bash
 # Some mozharness scripts assume base_work_dir is in
 # the current working directory, see bug 1279237
 cd $WORKSPACE
-cmd=\"python2.7 ${MOZHARNESS_PATH}/scripts/${MOZHARNESS_SCRIPT} ${config_cmds} ${@} \${@}\"
+cmd=\"python2.7 $WORKSPACE/${MOZHARNESS_SCRIPT} ${config_cmds} ${@} \${@}\"
 echo \"Running: \${cmd}\"
 exec \${cmd}" > ${mozharness_bin}
 chmod +x ${mozharness_bin}
 
 # In interactive mode, the user will be prompted with options for what to do.
 if ! $TASKCLUSTER_INTERACTIVE; then
   # run the given mozharness script and configs, but pass the rest of the
   # arguments in from our own invocation

--- a/taskcluster/taskgraph/transforms/tests/make_task_description.py
+++ b/taskcluster/taskgraph/transforms/tests/make_task_description.py
@@ -157,16 +157,17 @@ def docker_worker_setup(config, test, ta
         'name': 'level-{}-{}-test-workspace'.format(
             config.params['level'], config.params['project']),
         'mount-point': "/home/worker/workspace",
     }]
 
     env = worker['env'] = {
         'MOZHARNESS_CONFIG': ' '.join(mozharness['config']),
         'MOZHARNESS_SCRIPT': mozharness['script'],
+        'MOZHARNESS_URL': {'task-reference': mozharness_url},
         'MOZILLA_BUILD_URL': {'task-reference': installer_url},
         'NEED_PULSEAUDIO': 'true',
         'NEED_WINDOW_MANAGER': 'true',
     }
 
     if mozharness['set-moz-node-path']:
         env['MOZ_NODE_PATH'] = '/usr/local/bin/node'
 
@@ -192,24 +193,19 @@ def docker_worker_setup(config, test, ta
 
     # assemble the command line
     command = [
         '/home/worker/bin/run-task',
         # The workspace cache/volume is default owned by root:root.
         '--chown', '/home/worker/workspace',
     ]
 
-    # If we have a source checkout, run mozharness from it instead of
-    # downloading a zip file with the same content.
     if test['checkout']:
         docker_worker_support_vcs_checkout(config, test, taskdesc)
         command.extend(['--vcs-checkout', '/home/worker/checkouts/gecko'])
-        env['MOZHARNESS_PATH'] = '/home/worker/checkouts/gecko/testing/mozharness'
-    else:
-        env['MOZHARNESS_URL'] = {'task-reference': mozharness_url}
 
     command.extend([
         '--',
         '/home/worker/bin/test-linux.sh',
     ])
 
     if mozharness.get('no-read-buildbot-config'):
         command.append("--no-read-buildbot-config")