--- a/taskcluster/ci/source-test/kind.yml
+++ b/taskcluster/ci/source-test/kind.yml
@@ -13,16 +13,17 @@ transforms:
 jobs-from:
    - cram.yml
    - doc.yml
    - file-metadata.yml
    - mocha.yml
    - mozlint.yml
    - python.yml
    - webidl.yml
+   - manifest-upload.yml
 
 # This is used by run-task based tasks to lookup which build task it
 # should depend on based on its own platform.
 dependent-build-platforms:
    linux64-asan/opt:
       label: build-linux64-asan/opt
       target-name: target.tar.bz2
    linux64/debug:

new file mode 100644
--- /dev/null
+++ b/taskcluster/ci/source-test/manifest-upload.yml
@@ -0,0 +1,31 @@
+job-defaults:
+    platform: linux64/opt
+    treeherder:
+        kind: test
+        tier: 1
+    worker-type: aws-provisioner-v1/gecko-t-linux-xlarge
+    worker:
+        docker-image: {in-tree: "lint"}
+        max-run-time: 1800
+
+manifest-upload:
+    description: Generate and store the web-platform-tests manifest
+    treeherder:
+        symbol: Wm
+    index:
+        product: source
+        job-name: manifest-upload
+    run:
+        using: run-task
+        command: >
+            cd /builds/worker/checkouts/gecko
+            && ./mach wpt-manifest-update
+    worker:
+        artifacts:
+            - type: file
+              path: /builds/worker/checkouts/gecko/testing/web-platform/meta/MANIFEST.json
+              name: public/manifest
+        max-run-time: 3600
+    when:
+        files-changed:
+            - 'testing/web-platform/tests/**'