diff --git a/.github/workflows/preview_build.yml b/.github/workflows/preview_build.yml
new file mode 100644
index 0000000000..9aea890bce
--- /dev/null
+++ b/.github/workflows/preview_build.yml
@@ -0,0 +1,133 @@
+name: Preview build
+
+on:
+  repository_dispatch:
+    types:
+    - Preview*
+
+jobs:
+  preview:
+    name: Build preview
+
+    runs-on: ubuntu-20.04
+    container:
+      # If you change this version, change the number in the cache step too.
+      image: emscripten/emsdk:2.0.10
+      # uid=1001(runner) gid=121(docker)
+      options: -u 1001:121
+
+    steps:
+    - name: Update deployment status to in progress
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: in_progress
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        ref: ${{ github.event.client_payload.sha }}
+
+    - name: Name branch
+      run: |
+        name=$(echo "${{ github.event.client_payload.folder }}")
+        git checkout -b ${name}
+
+    - name: Setup cache
+      uses: actions/cache@v2
+      with:
+        path: /emsdk/upstream/emscripten/cache
+        key: 2.0.10-${{ runner.os }}
+
+    - name: Build (host tools)
+      run: |
+        mkdir build-host
+        cd build-host
+
+        echo "::group::CMake"
+        cmake .. -DOPTION_TOOLS_ONLY=ON
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        make -j$(nproc) tools
+        echo "::endgroup::"
+
+    - name: Install GCC problem matcher
+      uses: ammaraskar/gcc-problem-matcher@master
+
+    - name: Build
+      run: |
+        mkdir build
+        cd build
+
+        echo "::group::CMake"
+        emcmake cmake .. \
+          -DHOST_BINARY_DIR=../build-host \
+          -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+          # EOF
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        emmake make -j$(nproc)
+        echo "::endgroup::"
+
+    - name: Publish preview
+      run: |
+        # setuptools is missing in this Docker image, which breaks installing
+        # awscli. So we need to do this in two steps to recover sanity.
+        pip3 install setuptools
+        pip3 install awscli
+
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.data s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.html s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.js s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.wasm s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+
+        # Invalidate the cache of the CloudFront distribution
+        ~/.local/bin/aws cloudfront create-invalidation --distribution-id ${{ secrets.PREVIEW_CF_DISTRIBUTION_ID }} --paths "/${{ github.event.client_payload.folder }}/*"
+      env:
+        AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+        AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+
+    - name: Update deployment status to success
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: success
+        environment_url: https://preview.openttd.org/${{ github.event.client_payload.folder }}/
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: failure()
+      name: Update deployment status to failure
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: failure
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
diff --git a/.github/workflows/preview_label.yml b/.github/workflows/preview_label.yml
new file mode 100644
index 0000000000..6b3e17ea1a
--- /dev/null
+++ b/.github/workflows/preview_label.yml
@@ -0,0 +1,66 @@
+name: Preview label
+
+on:
+  pull_request_target:
+    types:
+    - labeled
+
+env:
+  TEAM_CORE_DEVELOPER: core-developers
+
+jobs:
+  check_preview_label:
+    name: Check for preview label
+    if: github.event.action == 'labeled' && github.event.label.name == 'preview'
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - name: Check if label was added by core developer
+      id: core_developer
+      continue-on-error: true
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /orgs/OpenTTD/teams/${{ env.TEAM_CORE_DEVELOPER }}/memberships/${{ github.event.sender.login }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'failure'
+      name: Remove preview label if not core developer
+      uses: octokit/request-action@v2.x
+      with:
+        route: DELETE /repos/{owner}/{repo}/issues/{issue_number}/labels/preview
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        issue_number: ${{ github.event.number }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'success'
+      name: Create deployment
+      id: deployment
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        ref: ${{ github.event.pull_request.head.sha }}
+        task: deploy:preview
+        auto_merge: false
+        required_contexts: "[]"
+        environment: preview-pr-${{ github.event.number }}
+        description: "Preview for Pull Request #${{ github.event.number }}"
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'success'
+      name: Trigger 'preview build'
+      uses: peter-evans/repository-dispatch@v1
+      with:
+        token: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+        event-type: "Preview build #${{ github.event.number }}"
+        client-payload: '{"folder": "pr${{ github.event.number }}", "sha": "${{ github.event.pull_request.head.sha }}", "deployment_id": "${{ fromJson(steps.deployment.outputs.data).id }}"}'
diff --git a/.github/workflows/preview_push.yml b/.github/workflows/preview_push.yml
new file mode 100644
index 0000000000..cb68c8f6ce
--- /dev/null
+++ b/.github/workflows/preview_push.yml
@@ -0,0 +1,66 @@
+name: Preview push
+
+on:
+  pull_request_target:
+    types:
+    - synchronize
+
+jobs:
+  check_new_preview:
+    name: Check preview needs update
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - name: Check if earlier preview exists
+      id: earlier_preview
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /repos/{owner}/{repo}/deployments
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        environment: preview-pr-${{ github.event.number }}
+        per_page: 1
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]'
+      name: Check for preview label
+      id: preview_label
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /repos/{owner}/{repo}/issues/{issue_number}/labels
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        issue_number: ${{ github.event.number }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]' && contains(fromJson(steps.preview_label.outputs.data).*.name, 'preview')
+      name: Create deployment
+      id: deployment
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        ref: ${{ github.event.pull_request.head.sha }}
+        task: deploy:preview
+        auto_merge: false
+        required_contexts: "[]"
+        environment: preview-pr-${{ github.event.number }}
+        description: "Preview for Pull Request #${{ github.event.number }}"
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]' && contains(fromJson(steps.preview_label.outputs.data).*.name, 'preview')
+      name: Trigger 'preview build'
+      uses: peter-evans/repository-dispatch@v1
+      with:
+        token: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+        event-type: "Preview build #${{ github.event.number }}"
+        client-payload: '{"folder": "pr${{ github.event.number }}", "sha": "${{ github.event.pull_request.head.sha }}", "deployment_id": "${{ fromJson(steps.deployment.outputs.data).id }}"}'