diff --git a/.github/actions/check-run/action.yml b/.github/actions/check-run/action.yml
deleted file mode 100644
index 3b666809dab5d..0000000000000
--- a/.github/actions/check-run/action.yml
+++ /dev/null
@@ -1,71 +0,0 @@
-name: "Check Run"
-description: "Create or update a check run. This is a simple wrapper around GitHub's checks API, https://docs.github.com/en/rest/checks/runs."
-inputs:
-  id:
-    description: "Check run ID to update. If not given, a new run will be created"
-  sha:
-    description: "The SHA of the commit."
-  name:
-    description: "The name of the check. For example, \"code-coverage\"."
-  status:
-    description: "The current status. Can be one of: `queued`, `in_progress`, `completed`"
-  conclusion:
-    description: "The final conclusion of the check. Can be one of: `action_required`, `cancelled`, `failure`, `neutral`, `success`, `skipped`, `timed_out`"
-  title:
-    description: "Title of the check. Shown in the PR's checks list."
-  summary:
-    description: "Summary of the check. Can contain Markdown."
-  token:
-    description: "Access token. Defaults to `github.token`."
-    default: ${{ github.token }}
-outputs:
-  id:
-    description: "Check run ID."
-    value: ${{ steps.run.outputs.id }}
-runs:
-  using: composite
-  steps:
-    - id: run
-      shell: bash
-      env:
-        ID: ${{ inputs.id }}
-        SHA: ${{ inputs.sha }}
-        NAME: ${{ inputs.name }}
-        STATUS: ${{ inputs.status }}
-        CONCLUSION: ${{ inputs.conclusion }}
-        TITLE: ${{ inputs.title }}
-        SUMMARY: ${{ inputs.summary }}
-        TOKEN: ${{ inputs.token }}
-      run: |
-        if [[ -n "$ID" ]]; then
-          METHOD=PATCH
-          URL="${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/check-runs/$ID"
-        else
-          METHOD=POST
-          URL="${GITHUB_API_URL}/repos/${GITHUB_REPOSITORY}/check-runs"
-        fi
-
-        DATA="{}"
-        if [[ -n "$NAME" ]]; then
-          DATA="$(jq --arg v "$NAME" '.name |= $v' <<<"$DATA")"
-        fi
-        if [[ -n "$SHA" ]]; then
-          DATA="$(jq --arg v "$SHA" '.head_sha |= $v' <<<"$DATA")"
-        fi
-        if [[ -n "$STATUS" ]]; then
-          DATA="$(jq --arg v "$STATUS" '.status |= $v' <<<"$DATA")"
-        fi
-        if [[ -n "$CONCLUSION" ]]; then
-          DATA="$(jq --arg v "$CONCLUSION" '.conclusion |= $v' <<<"$DATA")"
-        fi
-        if [[ -n "$TITLE" ]]; then
-          DATA="$(jq --arg v "$TITLE" '.output.title |= $v' <<<"$DATA")"
-        fi
-        if [[ -n "$SUMMARY" ]]; then
-          DATA="$(jq --arg v "$SUMMARY" '.output.summary |= $v' <<<"$DATA")"
-        fi
-
-        echo "Data: $DATA"
-        JSON="$(curl -v -X "$METHOD" --header "authorization: token $TOKEN" --url "$URL" --data "$DATA")"
-        echo "$JSON"
-        echo "::set-output name=id::$(jq -r .id <<<"$JSON")"
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1dd9c2bfb999a..4da3f0f829b1b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -128,6 +128,56 @@ jobs:
               comment_id: +COMMENT_ID,
             } );
 
+  upgrade_test:
+    name: Test plugin upgrades
+    runs-on: ubuntu-latest
+    needs: build
+    if: needs.build.outputs.any_plugins == 'true'
+    timeout-minutes: 10  # 2022-03-04: Successful runs seem to take about 3 minutes, but give some extra time for the downloads.
+    services:
+      db:
+        image: mariadb:latest
+        env:
+          MARIADB_ROOT_PASSWORD: wordpress
+        ports:
+          - 3306:3306
+        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=5
+    container:
+      image: ghcr.io/automattic/jetpack-wordpress-dev:latest
+      env:
+        WP_DOMAIN: localhost
+        WP_ADMIN_USER: wordpress
+        WP_ADMIN_EMAIL: wordpress@example.com
+        WP_ADMIN_PASSWORD: wordpress
+        WP_TITLE: Hello World
+        MYSQL_HOST: db:3306
+        MYSQL_DATABASE: wordpress
+        MYSQL_USER: root
+        MYSQL_PASSWORD: wordpress
+        HOST_PORT: 80
+      ports:
+        - 80:80
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          path: monorepo
+
+      - name: Download build artifact
+        uses: actions/download-artifact@v3
+        with:
+          name: jetpack-build
+      - name: Extract build archive
+        run: tar --xz -xvvf build.tar.xz
+
+      - name: Setup WordPress
+        run: monorepo/.github/files/test-plugin-update/setup.sh
+
+      - name: Prepare plugin zips
+        run: monorepo/.github/files/test-plugin-update/prepare-zips.sh
+
+      - name: Test upgrades
+        run: monorepo/.github/files/test-plugin-update/test.sh
+
   jetpack_beta:
     name: Create artifact for Jetpack Beta plugin
     runs-on: ubuntu-latest
diff --git a/.github/workflows/post-build.yml b/.github/workflows/post-build.yml
deleted file mode 100644
index 1b845d3bafee2..0000000000000
--- a/.github/workflows/post-build.yml
+++ /dev/null
@@ -1,206 +0,0 @@
-name: Post-Build
-on:
-  workflow_run:
-    types: [ 'completed' ]
-    workflows:
-      - Build
-concurrency:
-  # Cancel concurrent jobs on pull_request but not push, by including the run_id in the concurrency group for the latter.
-  group: post-build-${{ github.event.workflow_run.event == 'push' && github.run_id || 'pr' }}-${{ github.event.workflow_run.head_branch }}
-  cancel-in-progress: true
-
-env:
-  COMPOSER_ROOT_VERSION: "dev-trunk"
-  SUMMARY: Post-Build run [#${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) for Build run [#${{ github.event.workflow_run.id }}](${{ github.event.workflow_run.html_url }})
-
-# Note the job logic here is a bit unusual. That's because this workflow is triggered by `workflow_run`, and so is not shown on the PR by default.
-# Instead we have to manually report back, including where we could normally just skip or let a failure be handled.
-#  - If the "Build" job failed, we need to set our status as failed too (build_failed).
-#  - If the find_artifact job fails for some reason, we need a step to explicitly report that back.
-#  - If no plugins are found, we need to explicitly report back a "skipped" status.
-#  - And the upgrade_test job both explicitly sets "in progress" at its start and updates at its end.
-
-jobs:
-  build_failed:
-    name: Handle build failure
-    runs-on: ubuntu-latest
-    if: github.event.workflow_run.conclusion != 'success'
-    timeout-minutes: 2  # 2022-08-26: Seems like it should be fast.
-    steps:
-      - uses: actions/checkout@v3
-      - name: Create failed checks
-        uses: ./.github/actions/check-run
-        with:
-          name: Test plugin upgrades
-          sha: ${{ github.event.workflow_run.head_sha }}
-          conclusion: cancelled
-          title: Build failed
-          summary: |
-            ${{ env.SUMMARY }}
-
-            Post-build run aborted because the build did not succeed.
-
-  find_artifact:
-    name: Find artifact
-    runs-on: ubuntu-latest
-    if: github.event.workflow_run.conclusion == 'success'
-    timeout-minutes: 2  # 2022-08-26: Seems like it should be fast.
-    outputs:
-      zip_url: ${{ steps.run.outputs.zip_url }}
-      any_plugins: ${{ steps.run.outputs.any_plugins }}
-    steps:
-      - uses: actions/checkout@v3
-      - name: Find artifact
-        id: run
-        env:
-          TOKEN: ${{ github.token }}
-          URL: ${{ github.event.workflow_run.artifacts_url }}
-        run: |
-          for (( i=1; i<=5; i++ )); do
-            [[ $i -gt 1 ]] && sleep 10
-            echo "::group::Fetch list of artifacts (attempt $i/5)"
-            JSON="$(curl -v -L --get \
-              --header "Authorization: token $TOKEN" \
-              --url "$URL"
-            )"
-            echo "$JSON"
-            echo "::endgroup::"
-            ZIPURL="$(jq -r '.artifacts[] | select( .name == "jetpack-build" ) | .archive_download_url' <<<"$JSON")"
-            PLUGINS="$(jq -r '.artifacts[] | select( .name == "plugins" )' <<<"$JSON")"
-            if [[ -n "$ZIPURL" ]]; then
-              break
-            fi
-          done
-          [[ -z "$ZIPURL" ]] && { echo "::error::Failed to find artifact."; exit 1; }
-          echo "Zip URL: $ZIPURL"
-          echo "::set-output name=zip_url::${ZIPURL}"
-          if [[ -z "$PLUGINS" ]]; then
-            echo "Any plugins? No"
-            echo "::set-output name=any_plugins::false"
-          else
-            echo "Any plugins? Yes"
-            echo "::set-output name=any_plugins::true"
-          fi
-
-      - name: Create failed checks
-        if: ${{ ! success() }}
-        uses: ./.github/actions/check-run
-        with:
-          name: Test plugin upgrades
-          sha: ${{ github.event.workflow_run.head_sha }}
-          conclusion: failure
-          title: Failed to find build artifact
-          summary: |
-            ${{ env.SUMMARY }}
-
-            Post-build run aborted because the "Find artifact" step failed.
-
-  no_plugins:
-    name: Handle no-plugins
-    runs-on: ubuntu-latest
-    needs: find_artifact
-    if: needs.find_artifact.outputs.any_plugins == 'false'
-    timeout-minutes: 2  # 2022-08-26: Seems like it should be fast.
-    steps:
-      - uses: actions/checkout@v3
-      - name: Create skipped checks
-        uses: ./.github/actions/check-run
-        with:
-          name: Test plugin upgrades
-          sha: ${{ github.event.workflow_run.head_sha }}
-          conclusion: skipped
-          title: No plugins were built
-          summary: |
-            ${{ env.SUMMARY }}
-
-            Post-build run skipped because no plugins were built.
-
-  upgrade_test:
-    name: Test plugin upgrades
-    runs-on: ubuntu-latest
-    needs: find_artifact
-    if: needs.find_artifact.outputs.any_plugins == 'true'
-    timeout-minutes: 15  # 2022-08-26: Successful runs seem to take about 6 minutes, but give some extra time for the downloads.
-    services:
-      db:
-        image: mariadb:latest
-        env:
-          MARIADB_ROOT_PASSWORD: wordpress
-        ports:
-          - 3306:3306
-        options: --health-cmd="mysqladmin ping" --health-interval=10s --health-timeout=5s --health-retries=5
-    container:
-      image: ghcr.io/automattic/jetpack-wordpress-dev:latest
-      env:
-        WP_DOMAIN: localhost
-        WP_ADMIN_USER: wordpress
-        WP_ADMIN_EMAIL: wordpress@example.com
-        WP_ADMIN_PASSWORD: wordpress
-        WP_TITLE: Hello World
-        MYSQL_HOST: db:3306
-        MYSQL_DATABASE: wordpress
-        MYSQL_USER: root
-        MYSQL_PASSWORD: wordpress
-        HOST_PORT: 80
-      ports:
-        - 80:80
-    steps:
-      - uses: actions/checkout@v3
-        with:
-          path: monorepo
-
-      - name: Notify check in progress
-        id: create_run
-        uses: ./monorepo/.github/actions/check-run
-        with:
-          name: Test plugin upgrades
-          sha: ${{ github.event.workflow_run.head_sha }}
-          status: in_progress
-          title: Test started...
-          summary: |
-            ${{ env.SUMMARY }}
-
-            See run [#${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) for details.
-
-      - name: Download build artifact
-        env:
-          TOKEN: ${{ github.token }}
-          ZIPURL: ${{ needs.find_artifact.outputs.zip_url }}
-        shell: bash
-        run: |
-          for (( i=1; i<=2; i++ )); do
-            [[ $i -gt 1 ]] && sleep 10
-            echo "::group::Downloading artifact (attempt $i/2)"
-            curl -v -L --get \
-              --header "Authorization: token $TOKEN" \
-              --url "$ZIPURL" \
-              --output "artifact.zip"
-            echo "::endgroup::"
-            if [[ -e "artifact.zip" ]] && zipinfo artifact.zip &>/dev/null; then
-              break
-            fi
-          done
-          [[ ! -e "artifact.zip" ]] && { echo "::error::Failed to download artifact."; exit 1; }
-          unzip artifact.zip
-          tar --xz -xvvf build.tar.xz
-
-      - name: Setup WordPress
-        run: monorepo/.github/files/test-plugin-update/setup.sh
-
-      - name: Prepare plugin zips
-        run: monorepo/.github/files/test-plugin-update/prepare-zips.sh
-
-      - name: Test upgrades
-        run: monorepo/.github/files/test-plugin-update/test.sh
-
-      - name: Notify final status
-        if: always() && steps.create_run.outputs.id
-        uses: ./monorepo/.github/actions/check-run
-        with:
-          id: ${{ steps.create_run.outputs.id }}
-          conclusion: ${{ job.status }}
-          title: ${{ job.status == 'success' && 'Tests passed' || job.status == 'cancelled' && 'Cancelled' || 'Tests failed' }}
-          summary: |
-            ${{ env.SUMMARY }}
-
-            See run [#${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) for details.
diff --git a/.github/workflows/slack-workflow-failed.yml b/.github/workflows/slack-workflow-failed.yml
index c93f21544c702..f720b806c8067 100644
--- a/.github/workflows/slack-workflow-failed.yml
+++ b/.github/workflows/slack-workflow-failed.yml
@@ -7,7 +7,6 @@ on:
       - Build Docker
       - Tests
       - Gardening
-      - Post-Build
       - PR is up-to-date
     branches: [ 'trunk', '*/branch-*' ]