diff --git a/.github/workflows/build_all.yml b/.github/workflows/build_all.yml
index 1dd492617..21784c062 100644
--- a/.github/workflows/build_all.yml
+++ b/.github/workflows/build_all.yml
@@ -23,13 +23,15 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       cache-key: ${{ steps.cache-key.outputs.cache-key }}
+      matrix-alpine: ${{ steps.alpine.outputs.matrix }}
+      matrix-ubuntu: ${{ steps.ubuntu.outputs.matrix }}
     steps:
       - uses: actions/checkout@v5
         with:
           fetch-depth: 0
 
       - name: Install packages
-        run: python3 -m pip install git+https://github.com/mesonbuild/meson
+        run: python3 -m pip install PyYAML git+https://github.com/mesonbuild/meson
 
       - name: Calculate cache key
         id: cache-key
@@ -59,6 +61,40 @@ jobs:
           path: subprojects/packagecache
           enableCrossOsArchive: true
 
+      - name: Build Ubuntu matrix
+        id: ubuntu
+        shell: python tools/filter_matrix.py {0}
+        run: |
+          - platform: aarch64
+            runner: ubuntu-24.04-arm
+          - platform: ppc64le
+            runner: ubuntu-24.04-ppc64le
+            selfhosted: true
+          - platform: s390x
+            runner: ubuntu-24.04-s390x
+            selfhosted: true
+          - platform: x86_64
+            runner: ubuntu-latest
+
+      - name: Build Alpine matrix
+        id: alpine
+        shell: python tools/filter_matrix.py {0}
+        run: |
+          - platform: aarch64
+            runner: ubuntu-24.04-arm
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
+          - platform: ppc64le
+            runner: ubuntu-24.04-ppc64le
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/ppc64le/apk.static#!sha256!96ba92b49c8cc97fad06f0dfe3c50ec25c3344890e479999ded8752bf9e80d7f'
+            selfhosted: true
+          - platform: s390x
+            runner: ubuntu-24.04-s390x
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/s390x/apk.static#!sha256!368996f2908ec8f10f1de500bc97a9bd1c3b0b46ce0bd44983ac09862cbab6d5'
+            selfhosted: true
+          - platform: x86_64
+            runner: ubuntu-latest
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
+
   Ubuntu:
     if: github.event_name != 'schedule' || github.repository == 'mesonbuild/wrapdb'
     name: Ubuntu (${{ matrix.platform }})
@@ -66,11 +102,7 @@ jobs:
     needs: prelude
     strategy:
       matrix:
-        include:
-          - platform: aarch64
-            runner: ubuntu-24.04-arm
-          - platform: x86_64
-            runner: ubuntu-latest
+        include: ${{ fromJson(needs.prelude.outputs.matrix-ubuntu) }}
     steps:
       - uses: actions/checkout@v5
         with:
@@ -101,13 +133,7 @@ jobs:
     needs: prelude
     strategy:
       matrix:
-        include:
-          - platform: aarch64
-            runner: ubuntu-24.04-arm
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
-          - platform: x86_64
-            runner: ubuntu-latest
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
+        include: ${{ fromJson(needs.prelude.outputs.matrix-alpine) }}
     steps:
       - uses: jirutka/setup-alpine@v1
         with:
diff --git a/.github/workflows/sanity_checks.yml b/.github/workflows/sanity_checks.yml
index 715d217eb..b867f96fd 100644
--- a/.github/workflows/sanity_checks.yml
+++ b/.github/workflows/sanity_checks.yml
@@ -18,6 +18,8 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       cache-key: ${{ steps.cache-key.outputs.cache-key }}
+      matrix-alpine: ${{ steps.alpine.outputs.matrix }}
+      matrix-ubuntu: ${{ steps.ubuntu.outputs.matrix }}
     steps:
       - uses: actions/checkout@v5
         with:
@@ -25,7 +27,7 @@ jobs:
 
       - name: Install packages
         run: |
-          python3 -m pip install license-expression
+          python3 -m pip install license-expression PyYAML
           python3 -m pip install --pre meson
 
       - name: Calculate cache key
@@ -59,6 +61,53 @@ jobs:
         run: |
           ./tools/fake_tty.py ./tools/sanity_checks.py
 
+      - name: Build Ubuntu matrix
+        id: ubuntu
+        shell: python tools/filter_matrix.py {0}
+        run: |
+          - platform: aarch64
+            runner: ubuntu-24.04-arm
+            python: 3.8
+          - platform: ppc64le
+            runner: ubuntu-24.04-ppc64le
+            python: 3.13
+            selfhosted: true
+          - platform: s390x
+            runner: ubuntu-24.04-s390x
+            python: 3.13
+            selfhosted: true
+          - platform: x86_64
+            runner: ubuntu-latest
+            python: 3.13
+
+      - name: Build Alpine matrix
+        id: alpine
+        shell: python tools/filter_matrix.py {0}
+        run: |
+          - platform: aarch64
+            runner: ubuntu-24.04-arm
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
+          - platform: armv7
+            runner: ubuntu-24.04-arm
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
+          - platform: ppc64le
+            runner: ubuntu-24.04-ppc64le
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/ppc64le/apk.static#!sha256!96ba92b49c8cc97fad06f0dfe3c50ec25c3344890e479999ded8752bf9e80d7f'
+            selfhosted: true
+          - platform: riscv64
+            runner: ubuntu-24.04-arm
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
+          - platform: s390x
+            runner: ubuntu-24.04-s390x
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/s390x/apk.static#!sha256!368996f2908ec8f10f1de500bc97a9bd1c3b0b46ce0bd44983ac09862cbab6d5'
+            selfhosted: true
+          - platform: x86
+            runner: ubuntu-latest
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
+          - platform: x86_64
+            runner: ubuntu-latest
+            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
+
   Ubuntu:
     name: Ubuntu (${{ matrix.platform }})
     runs-on: ${{ matrix.runner }}
@@ -66,13 +115,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        include:
-          - platform: aarch64
-            runner: ubuntu-24.04-arm
-            python: 3.8
-          - platform: x86_64
-            runner: ubuntu-latest
-            python: 3.13
+        include: ${{ fromJson(needs.prelude.outputs.matrix-ubuntu) }}
     steps:
       - uses: actions/checkout@v5
         with:
@@ -118,25 +161,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        include:
-          - platform: aarch64
-            runner: ubuntu-24.04-arm
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
-          - platform: armv7
-            runner: ubuntu-24.04-arm
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
-          - platform: ppc64le
-            runner: ubuntu-24.04-arm
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
-          - platform: riscv64
-            runner: ubuntu-24.04-arm
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/aarch64/apk.static#!sha256!27a975638ddc95a411c9f17c63383e335da9edf6bb7de2281d950c291a11f878'
-          - platform: x86
-            runner: ubuntu-latest
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
-          - platform: x86_64
-            runner: ubuntu-latest
-            apk-tools-url: 'https://gitlab.alpinelinux.org/api/v4/projects/5/packages/generic/v2.14.7/x86_64/apk.static#!sha256!bdd044e0fd6cc388c5e571e1093efa5f35f7767cc5aa338b0a2576a429009a62'
+        include: ${{ fromJson(needs.prelude.outputs.matrix-alpine) }}
     steps:
       - uses: actions/checkout@v5
         with:
diff --git a/tools/filter_matrix.py b/tools/filter_matrix.py
new file mode 100755
index 000000000..7dd6a0f13
--- /dev/null
+++ b/tools/filter_matrix.py
@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+# Copyright 2025 Benjamin Gilbert <bgilbert@backtick.net>
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     https://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import os
+import sys
+import yaml
+import typing as T
+
+UPSTREAM_OWNER = 'mesonbuild'
+
+with open(sys.argv[1]) as f:
+    jobs: list[dict[str, T.Any]] = yaml.safe_load(f)
+
+if os.environ['GITHUB_REPOSITORY_OWNER'] != UPSTREAM_OWNER:
+    jobs = [j for j in jobs if not j.get('selfhosted', False)]
+
+with open(os.environ['GITHUB_OUTPUT'], 'a') as f:
+    f.write('matrix=')
+    json.dump(jobs, f, separators=(',', ':'))
+    f.write('\n')