diff --git a/browser/config/mozconfigs/linux32/profile-generate b/browser/config/mozconfigs/linux32/profile-generate
index 5baa2a5334fd..426f4651b7c3 100644
--- a/browser/config/mozconfigs/linux32/profile-generate
+++ b/browser/config/mozconfigs/linux32/profile-generate
@@ -1,6 +1,5 @@
 . $topsrcdir/browser/config/mozconfigs/linux32/nightly
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=0"
 
diff --git a/browser/config/mozconfigs/linux32/rusttests b/browser/config/mozconfigs/linux32/rusttests
index eb1163db3427..e487cfd3df8b 100644
--- a/browser/config/mozconfigs/linux32/rusttests
+++ b/browser/config/mozconfigs/linux32/rusttests
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 mk_add_options MOZ_MAKE_FLAGS=--output-sync=line
diff --git a/browser/config/mozconfigs/linux32/rusttests-debug b/browser/config/mozconfigs/linux32/rusttests-debug
index d1aad0143b6b..15c43e5c8a8f 100644
--- a/browser/config/mozconfigs/linux32/rusttests-debug
+++ b/browser/config/mozconfigs/linux32/rusttests-debug
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 mk_add_options MOZ_MAKE_FLAGS=--output-sync=line
diff --git a/browser/config/mozconfigs/linux64/debug-searchfox-clang b/browser/config/mozconfigs/linux64/debug-searchfox-clang
index 2761b6458260..425f92dcf964 100644
--- a/browser/config/mozconfigs/linux64/debug-searchfox-clang
+++ b/browser/config/mozconfigs/linux64/debug-searchfox-clang
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_CHECK=0
 
diff --git a/browser/config/mozconfigs/linux64/debug-static-analysis-clang b/browser/config/mozconfigs/linux64/debug-static-analysis-clang
index ca69c5982113..6c0743cff6e2 100644
--- a/browser/config/mozconfigs/linux64/debug-static-analysis-clang
+++ b/browser/config/mozconfigs/linux64/debug-static-analysis-clang
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/build/mozconfig.common"
diff --git a/browser/config/mozconfigs/linux64/profile-generate b/browser/config/mozconfigs/linux64/profile-generate
index 5542f8e478f5..d6b195d3d9c3 100644
--- a/browser/config/mozconfigs/linux64/profile-generate
+++ b/browser/config/mozconfigs/linux64/profile-generate
@@ -1,6 +1,5 @@
 . $topsrcdir/browser/config/mozconfigs/linux64/nightly
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=0"
 
diff --git a/browser/config/mozconfigs/linux64/rusttests b/browser/config/mozconfigs/linux64/rusttests
index 4d8b5bbf966d..acf24719bdc7 100644
--- a/browser/config/mozconfigs/linux64/rusttests
+++ b/browser/config/mozconfigs/linux64/rusttests
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 mk_add_options MOZ_MAKE_FLAGS=--output-sync=line
diff --git a/browser/config/mozconfigs/linux64/rusttests-debug b/browser/config/mozconfigs/linux64/rusttests-debug
index 21f17e1be31c..d9422e1dd09f 100644
--- a/browser/config/mozconfigs/linux64/rusttests-debug
+++ b/browser/config/mozconfigs/linux64/rusttests-debug
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 mk_add_options MOZ_MAKE_FLAGS=--output-sync=line
diff --git a/browser/config/mozconfigs/linux64/tup b/browser/config/mozconfigs/linux64/tup
index 2f76b1f7f432..208d9263c509 100644
--- a/browser/config/mozconfigs/linux64/tup
+++ b/browser/config/mozconfigs/linux64/tup
@@ -1,7 +1,6 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_PACKAGE=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_UPLOAD=0
 MOZ_AUTOMATION_UPLOAD_SYMBOLS=0
 
diff --git a/browser/config/mozconfigs/macosx64/debug-searchfox b/browser/config/mozconfigs/macosx64/debug-searchfox
index 25c67358f66e..533754701970 100644
--- a/browser/config/mozconfigs/macosx64/debug-searchfox
+++ b/browser/config/mozconfigs/macosx64/debug-searchfox
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_CHECK=0
 
diff --git a/browser/config/mozconfigs/macosx64/debug-static-analysis b/browser/config/mozconfigs/macosx64/debug-static-analysis
index 5e713b2c5f5d..5dfa113d066c 100644
--- a/browser/config/mozconfigs/macosx64/debug-static-analysis
+++ b/browser/config/mozconfigs/macosx64/debug-static-analysis
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . $topsrcdir/build/macosx/mozconfig.common
diff --git a/browser/config/mozconfigs/macosx64/opt-static-analysis b/browser/config/mozconfigs/macosx64/opt-static-analysis
index ad743267cb88..eaa95df9e7a2 100644
--- a/browser/config/mozconfigs/macosx64/opt-static-analysis
+++ b/browser/config/mozconfigs/macosx64/opt-static-analysis
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . $topsrcdir/build/macosx/mozconfig.common
diff --git a/browser/config/mozconfigs/macosx64/profile-generate b/browser/config/mozconfigs/macosx64/profile-generate
index 05fbad79b34a..b0a7a20da958 100644
--- a/browser/config/mozconfigs/macosx64/profile-generate
+++ b/browser/config/mozconfigs/macosx64/profile-generate
@@ -1,6 +1,5 @@
 . $topsrcdir/browser/config/mozconfigs/macosx64/nightly
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=0"
 
diff --git a/browser/config/mozconfigs/win32/debug-static-analysis b/browser/config/mozconfigs/win32/debug-static-analysis
index 38e207924b0d..c4fbdc93e886 100644
--- a/browser/config/mozconfigs/win32/debug-static-analysis
+++ b/browser/config/mozconfigs/win32/debug-static-analysis
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/build/mozconfig.win-common"
diff --git a/browser/config/mozconfigs/win32/profile-generate b/browser/config/mozconfigs/win32/profile-generate
index 80ed9c78a516..73a620fc42c3 100644
--- a/browser/config/mozconfigs/win32/profile-generate
+++ b/browser/config/mozconfigs/win32/profile-generate
@@ -1,6 +1,5 @@
 . $topsrcdir/browser/config/mozconfigs/win32/nightly
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=0"
 
diff --git a/browser/config/mozconfigs/win32/rusttests b/browser/config/mozconfigs/win32/rusttests
index fa5b254c247b..da86508ba7dc 100644
--- a/browser/config/mozconfigs/win32/rusttests
+++ b/browser/config/mozconfigs/win32/rusttests
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/browser/config/mozconfigs/win32/nightly"
diff --git a/browser/config/mozconfigs/win32/rusttests-debug b/browser/config/mozconfigs/win32/rusttests-debug
index 25a848fa78b1..999632f14cc3 100644
--- a/browser/config/mozconfigs/win32/rusttests-debug
+++ b/browser/config/mozconfigs/win32/rusttests-debug
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/browser/config/mozconfigs/win32/debug"
diff --git a/browser/config/mozconfigs/win64/debug-searchfox b/browser/config/mozconfigs/win64/debug-searchfox
index 2a13adca90ed..de4142f5f57d 100644
--- a/browser/config/mozconfigs/win64/debug-searchfox
+++ b/browser/config/mozconfigs/win64/debug-searchfox
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_CHECK=0
 
diff --git a/browser/config/mozconfigs/win64/profile-generate b/browser/config/mozconfigs/win64/profile-generate
index eb110078ef51..8f08214800e9 100644
--- a/browser/config/mozconfigs/win64/profile-generate
+++ b/browser/config/mozconfigs/win64/profile-generate
@@ -1,6 +1,5 @@
 . $topsrcdir/browser/config/mozconfigs/win64/nightly
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=0"
 
diff --git a/browser/config/mozconfigs/win64/rusttests b/browser/config/mozconfigs/win64/rusttests
index bdd35cccb413..2d07562100b0 100644
--- a/browser/config/mozconfigs/win64/rusttests
+++ b/browser/config/mozconfigs/win64/rusttests
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/browser/config/mozconfigs/win64/nightly"
diff --git a/browser/config/mozconfigs/win64/rusttests-debug b/browser/config/mozconfigs/win64/rusttests-debug
index 7ca826ebd400..ccf32fc8e5f3 100644
--- a/browser/config/mozconfigs/win64/rusttests-debug
+++ b/browser/config/mozconfigs/win64/rusttests-debug
@@ -1,5 +1,4 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 
 . "$topsrcdir/browser/config/mozconfigs/win64/debug"
diff --git a/build/mozconfig.automation b/build/mozconfig.automation
index 9395b115fff1..b3a406881fe1 100644
--- a/build/mozconfig.automation
+++ b/build/mozconfig.automation
@@ -12,9 +12,12 @@
 mk_add_options "export MOZ_AUTOMATION_BUILD_SYMBOLS=${MOZ_AUTOMATION_BUILD_SYMBOLS-1}"
 mk_add_options "export MOZ_AUTOMATION_L10N_CHECK=${MOZ_AUTOMATION_L10N_CHECK-0}"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE=${MOZ_AUTOMATION_PACKAGE-1}"
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=${MOZ_AUTOMATION_PACKAGE_TESTS-1}"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=${MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES-1}"
 mk_add_options "export MOZ_AUTOMATION_UPLOAD=${MOZ_AUTOMATION_UPLOAD-1}"
 mk_add_options "export MOZ_AUTOMATION_CHECK=${MOZ_AUTOMATION_CHECK-1}"
 
+# The following variables are expected to be exported by Taskcluster
+# configuration files rather than mozconfig files
+mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=${MOZ_AUTOMATION_PACKAGE_TESTS-0}"
+
 export MOZ_AUTOMATION_MOZCONFIG=1
diff --git a/js/src/devtools/rootAnalysis/mozconfig.haz b/js/src/devtools/rootAnalysis/mozconfig.haz
index 5dfda064f5eb..4089eaf9411e 100644
--- a/js/src/devtools/rootAnalysis/mozconfig.haz
+++ b/js/src/devtools/rootAnalysis/mozconfig.haz
@@ -13,7 +13,6 @@ MOZ_HAZARD=1
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_PACKAGE=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_UPLOAD=0
 
 ac_add_options --enable-js-shell
diff --git a/mobile/android/config/mozconfigs/android-api-16-gradle-dependencies/nightly b/mobile/android/config/mozconfigs/android-api-16-gradle-dependencies/nightly
index f37a61bd9f4b..8fca11e6fb92 100644
--- a/mobile/android/config/mozconfigs/android-api-16-gradle-dependencies/nightly
+++ b/mobile/android/config/mozconfigs/android-api-16-gradle-dependencies/nightly
@@ -2,7 +2,6 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_PACKAGE=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_UPLOAD=0
 MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0
 
diff --git a/mobile/android/config/mozconfigs/android-api-16/nightly-android-lints b/mobile/android/config/mozconfigs/android-api-16/nightly-android-lints
index 3249ba893aae..dec7586eb318 100644
--- a/mobile/android/config/mozconfigs/android-api-16/nightly-android-lints
+++ b/mobile/android/config/mozconfigs/android-api-16/nightly-android-lints
@@ -2,7 +2,6 @@
 MOZ_AUTOMATION_BUILD_SYMBOLS=0
 MOZ_AUTOMATION_L10N_CHECK=0
 MOZ_AUTOMATION_PACKAGE=0
-MOZ_AUTOMATION_PACKAGE_TESTS=0
 MOZ_AUTOMATION_UPLOAD=0
 MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0
 
diff --git a/mobile/android/config/mozconfigs/android-api-16/profile-generate b/mobile/android/config/mozconfigs/android-api-16/profile-generate
index de12b216dc0f..e70927f5fc80 100644
--- a/mobile/android/config/mozconfigs/android-api-16/profile-generate
+++ b/mobile/android/config/mozconfigs/android-api-16/profile-generate
@@ -1,6 +1,5 @@
 . "$topsrcdir/mobile/android/config/mozconfigs/android-api-16/nightly"
 
-mk_add_options "export MOZ_AUTOMATION_PACKAGE_TESTS=0"
 mk_add_options "export MOZ_AUTOMATION_PACKAGE_GENERATED_SOURCES=0"
 
 ac_add_options --enable-profile-generate
diff --git a/taskcluster/ci/build/android.yml b/taskcluster/ci/build/android.yml
index 7e086f470322..71f62b0a768e 100644
--- a/taskcluster/ci/build/android.yml
+++ b/taskcluster/ci/build/android.yml
@@ -55,6 +55,7 @@ android-api-16/debug:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -146,6 +147,7 @@ android-api-16/opt:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -169,6 +171,7 @@ android-api-16/pgo:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -218,6 +221,7 @@ android-aarch64/opt:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -241,6 +245,7 @@ android-aarch64/pgo:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -262,6 +267,7 @@ android-aarch64/debug:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -312,6 +318,7 @@ android-x86_64/opt:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android-x86/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
@@ -361,6 +368,7 @@ android-x86_64/debug:
     worker:
         env:
             TOOLTOOL_MANIFEST: "mobile/android/config/tooltool-manifests/android-x86/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         config: ["builds/releng_base_android_64_builds.py"]
diff --git a/taskcluster/ci/build/linux.yml b/taskcluster/ci/build/linux.yml
index d1b6344106fd..38c945f7cb49 100644
--- a/taskcluster/ci/build/linux.yml
+++ b/taskcluster/ci/build/linux.yml
@@ -16,6 +16,8 @@ linux64/opt:
     worker-type: b-linux
     worker:
         max-run-time: 7200
+        env:
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -133,6 +135,8 @@ linux64/debug:
     worker-type: b-linux
     worker:
         max-run-time: 5400
+        env:
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -214,6 +218,8 @@ linux64-devedition/opt:
     worker-type: b-linux
     worker:
         max-run-time: 7200
+        env:
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -617,6 +623,8 @@ linux-shippable/opt:
     worker:
         docker-image: {in-tree: debian7-i386-build}
         max-run-time: 9000
+        env:
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -697,6 +705,7 @@ linux64-asan/opt:
         env:
             PERFHERDER_EXTRA_OPTIONS: "opt asan"
             ASAN_OPTIONS: "detect_leaks=0"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
         max-run-time: 5400
     run:
         using: mozharness
@@ -1027,6 +1036,8 @@ linux64-shippable/opt:
     worker-type: b-linux
     worker:
         max-run-time: 9000
+        env:
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -1231,6 +1242,7 @@ linux64-ccov/opt:
             MOZ_LOW_PARALLELISM_BUILD: '1'
             FORCE_GCC: '1'
             RUSTC_BOOTSTRAP: '1'
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
diff --git a/taskcluster/ci/build/macosx.yml b/taskcluster/ci/build/macosx.yml
index 71f13daea43d..e1efb4c6cdbd 100644
--- a/taskcluster/ci/build/macosx.yml
+++ b/taskcluster/ci/build/macosx.yml
@@ -18,6 +18,7 @@ macosx64/debug:
         max-run-time: 5400
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/macosx64/cross-releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -197,6 +198,7 @@ macosx64-devedition/opt:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/macosx64/cross-releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
@@ -335,6 +337,7 @@ macosx64-shippable/opt:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/macosx64/cross-releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         using: mozharness
         actions: [get-secrets, build]
diff --git a/taskcluster/ci/build/windows-mingw.yml b/taskcluster/ci/build/windows-mingw.yml
index e7f0bfbd85ad..47e38bb79094 100644
--- a/taskcluster/ci/build/windows-mingw.yml
+++ b/taskcluster/ci/build/windows-mingw.yml
@@ -25,6 +25,7 @@ win32-mingwclang/opt:
     worker:
         env:
             PERFHERDER_EXTRA_OPTIONS: "opt 32 clang"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         config:
             - builds/releng_base_firefox.py
@@ -57,6 +58,7 @@ win32-mingwclang/debug:
     worker:
         env:
             PERFHERDER_EXTRA_OPTIONS: "debug 32 clang"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         config:
             - builds/releng_base_firefox.py
@@ -88,6 +90,7 @@ win64-mingwclang/opt:
     worker:
         env:
             PERFHERDER_EXTRA_OPTIONS: "opt 64 clang"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         config:
             - builds/releng_base_firefox.py
@@ -120,6 +123,7 @@ win64-mingwclang/debug:
     worker:
         env:
             PERFHERDER_EXTRA_OPTIONS: "debug 64 clang"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         config:
             - builds/releng_base_firefox.py
diff --git a/taskcluster/ci/build/windows.yml b/taskcluster/ci/build/windows.yml
index fb61c7d77487..0a035906ad5f 100755
--- a/taskcluster/ci/build/windows.yml
+++ b/taskcluster/ci/build/windows.yml
@@ -28,6 +28,7 @@ win32/debug:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win32/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -65,6 +66,7 @@ win32/opt:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win32/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -103,6 +105,7 @@ win64/debug:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -214,6 +217,7 @@ win64/opt:
         max-run-time: 7200
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -303,6 +307,7 @@ win32-shippable/opt:
         max-run-time: 10800
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win32/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -344,6 +349,7 @@ win64-shippable/opt:
         max-run-time: 10800
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -677,6 +683,7 @@ win64-ccov/opt:
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
             RUSTC_BOOTSTRAP: '1'
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -749,6 +756,7 @@ win64-asan/opt:
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
             PERFHERDER_EXTRA_OPTIONS: "opt asan"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -884,6 +892,7 @@ win32-devedition/opt:
         max-run-time: 10800
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win32/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         script: mozharness/scripts/fx_desktop_build.py
         secrets: true
@@ -927,6 +936,7 @@ win64-devedition/opt:
         max-run-time: 10800
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/releng.manifest"
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         options: [append-env-variables-from-configs]
         script: mozharness/scripts/fx_desktop_build.py
@@ -996,6 +1006,10 @@ win64-aarch64/opt:
     attributes:
         enable-build-signing: true
         enable-full-crashsymbols: true
+        # We need to package tests in order for the win64-aarch64-eme artifact
+        # build to fetch them, even though no tests run against this task
+        # directly.
+        skip-verify-test-packaging: true
     treeherder:
         platform: windows2012-aarch64/opt
         symbol: B
@@ -1006,6 +1020,7 @@ win64-aarch64/opt:
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/aarch64.manifest"
             PERFHERDER_EXTRA_OPTIONS: aarch64
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         options: [append-env-variables-from-configs]
@@ -1074,6 +1089,9 @@ win64-aarch64-shippable/opt:
     attributes:
         shippable: true
         enable-full-crashsymbols: true
+        # Skip the test packaging check because we copy test packages from
+        # another build task rather than generating them in this task.
+        skip-verify-test-packaging: true
     shipping-phase: build
     shipping-product: firefox
     treeherder:
@@ -1088,7 +1106,6 @@ win64-aarch64-shippable/opt:
             PERFHERDER_EXTRA_OPTIONS: aarch64
             MOZ_ARTIFACT_TASK: {task-reference: '<win64-aarch64-opt>'}
             MOZ_ARTIFACT_TASK_WIN32_OPT: {task-reference: '<win32-opt>'}
-            MOZ_AUTOMATION_PACKAGE_TESTS: '0'
             USE_ARTIFACT: '1'
     run:
         actions: [get-secrets, build]
@@ -1165,6 +1182,10 @@ win64-aarch64-shippable-no-eme/opt:
         type: shippable
     attributes:
         enable-full-crashsymbols: true
+        # We need to package tests in order for the actual
+        # win64-aarch64-shippable/opt build to copy them from this task, even
+        # though no tests run against this task directly.
+        skip-verify-test-packaging: true
     shipping-phase: build
     shipping-product: firefox
     treeherder:
@@ -1177,6 +1198,7 @@ win64-aarch64-shippable-no-eme/opt:
         env:
             TOOLTOOL_MANIFEST: "browser/config/tooltool-manifests/win64/aarch64.manifest"
             PERFHERDER_EXTRA_OPTIONS: aarch64-no-eme
+            MOZ_AUTOMATION_PACKAGE_TESTS: "1"
     run:
         actions: [get-secrets, build]
         options: [append-env-variables-from-configs]
diff --git a/taskcluster/docs/attributes.rst b/taskcluster/docs/attributes.rst
index f3678720765a..96727b7801dd 100644
--- a/taskcluster/docs/attributes.rst
+++ b/taskcluster/docs/attributes.rst
@@ -340,3 +340,10 @@ run-visual-metrics
 ==================
 If set to true, will run the visual metrics task on the provided
 video files.
+
+skip-verify-test-packaging
+==================
+If set to true, this task will not be checked to see that
+MOZ_AUTOMATION_PACKAGE_TESTS is set correctly based on whether or not the task
+has dependent tests. This should only be used in very unique situations, such
+as Windows AArch64 builds that copy test packages between build tasks.
diff --git a/taskcluster/taskgraph/util/verify.py b/taskcluster/taskgraph/util/verify.py
index 5e19d11cc619..c2b4d0574cf5 100644
--- a/taskcluster/taskgraph/util/verify.py
+++ b/taskcluster/taskgraph/util/verify.py
@@ -261,3 +261,41 @@ def verify_nightly_no_sccache(task, taskgraph, scratch_pad, graph_config):
         if task.task.get('payload', {}).get('env', {}).get('USE_SCCACHE'):
             raise Exception(
                 'Nightly job {} cannot use sccache'.format(task.label))
+
+
+@verifications.add('full_task_graph')
+def verify_test_packaging(task, taskgraph, scratch_pad, graph_config):
+    if task is None:
+        for task in taskgraph.tasks.itervalues():
+            if task.kind == 'build' and not task.attributes.get('skip-verify-test-packaging'):
+                build_env = task.task.get('payload', {}).get('env', {})
+                package_tests = build_env.get('MOZ_AUTOMATION_PACKAGE_TESTS')
+                shippable = task.attributes.get('shippable', False)
+                build_has_tests = scratch_pad.get(task.label)
+
+                if package_tests != '1':
+                    # Shippable builds should always package tests.
+                    if shippable:
+                        raise Exception('Build job {} is shippable and does not specify '
+                                        'MOZ_AUTOMATION_PACKAGE_TESTS=1 in the '
+                                        'environment.'.format(task.label))
+
+                    # Build tasks in the scratch pad have tests dependent on
+                    # them, so we need to package tests during build.
+                    if build_has_tests:
+                        raise Exception(
+                            'Build job {} has tests dependent on it and does not specify '
+                            'MOZ_AUTOMATION_PACKAGE_TESTS=1 in the environment'.format(task.label))
+                else:
+                    # Build tasks that aren't in the scratch pad have no
+                    # dependent tests, so we shouldn't package tests.
+                    if not build_has_tests:
+                        raise Exception(
+                            'Build job {} has no tests, but specifies '
+                            'MOZ_AUTOMATION_PACKAGE_TESTS={} in the environment. '
+                            'Unset MOZ_AUTOMATION_PACKAGE_TESTS in the task definition '
+                            'to fix.'.format(task.label, package_tests))
+        return
+    if task.kind == 'test':
+        build_task = taskgraph[task.dependencies['build']]
+        scratch_pad[build_task.label] = 1