diff --git a/.github/workflows/modgc.yml b/.github/workflows/modgc.yml
new file mode 100644
index 0000000000..dc6223baa1
--- /dev/null
+++ b/.github/workflows/modgc.yml
@@ -0,0 +1,204 @@
+name: ModGC
+on:
+  push:
+    paths-ignore:
+      - 'doc/**'
+      - '**/man/*'
+      - '**.md'
+      - '**.rdoc'
+      - '**/.document'
+      - '.*.yml'
+  pull_request:
+    # Do not use paths-ignore for required status checks
+    # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
+  merge_group:
+
+concurrency:
+  group: ${{ github.workflow }} / ${{ startsWith(github.event_name, 'pull') && github.ref_name || github.sha }}
+  cancel-in-progress: ${{ startsWith(github.event_name, 'pull') }}
+
+permissions:
+  contents: read
+
+jobs:
+  check:
+    strategy:
+      matrix:
+        gc:
+          - name: default
+          - name: mmtk
+            mmtk_plan: MarkSweep
+            mmtk_build: release
+        os: [macos-latest, ubuntu-latest]
+        include:
+          - test_task: check
+      fail-fast: false
+
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
+      RUBY_DEBUG: ci
+
+    runs-on: ${{ matrix.os }}
+
+    if: >-
+      ${{!(false
+      || contains(github.event.head_commit.message, '[DOC]')
+      || contains(github.event.head_commit.message, 'Document')
+      || contains(github.event.pull_request.title, '[DOC]')
+      || contains(github.event.pull_request.title, 'Document')
+      || contains(github.event.pull_request.labels.*.name, 'Documentation')
+      || (github.event_name == 'push' && github.event.pull_request.user.login == 'dependabot[bot]')
+      )}}
+
+    steps:
+      - uses: actions/checkout@d632683dd7b4114ad314bca15554477dd762a938 # v4.2.0
+        with:
+          sparse-checkout-cone-mode: false
+          sparse-checkout: /.github
+
+      - name: Install libraries (macOS)
+        uses: ./.github/actions/setup/macos
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Install libraries (Ubuntu)
+        uses: ./.github/actions/setup/ubuntu
+        if: ${{ contains(matrix.os, 'ubuntu') }}
+
+      - uses: ruby/setup-ruby@a6e6f86333f0a2523ece813039b8b4be04560854 # v1.190.0
+        with:
+          ruby-version: '3.0'
+          bundler: none
+        if: ${{ contains(matrix.os, 'ubuntu') }}
+
+      - uses: ./.github/actions/setup/directories
+        with:
+          srcdir: src
+          builddir: build
+          makeup: true
+          clean: true
+          dummy-files: false
+          # Set fetch-depth: 10 so that Launchable can receive commits information.
+          fetch-depth: 10
+
+      - name: make sure that kern.coredump=1
+        run: |
+          sysctl -n kern.coredump
+          sudo sysctl -w kern.coredump=1
+          sudo chmod -R +rwx /cores/
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Delete unused SDKs
+        # To free up disk space to not run out during the run
+        run: |
+          sudo rm -rf ~/.dotnet
+          sudo rm -rf /Library/Android
+          sudo rm -rf /Library/Developer/CoreSimulator
+        continue-on-error: true
+        if: ${{ contains(matrix.os, 'macos') }}
+
+      - name: Setup Ruby GC Directory
+        run: |
+          if [ "${{ contains(matrix.os, 'macos') }}" == "true" ]; then
+            echo "MODULAR_GC_DIR=/Users/runner/ruby_gc" >> $GITHUB_ENV
+          else
+            echo "MODULAR_GC_DIR=/home/runner/ruby_gc" >> $GITHUB_ENV
+          fi
+
+      - name: Run configure
+        env:
+          arch: ${{ matrix.arch }}
+        run: >-
+          $SETARCH ../src/configure -C --disable-install-doc --with-modular-gc=${{ env.MODULAR_GC_DIR }}
+          ${arch:+--target=$arch-$OSTYPE --host=$arch-$OSTYPE}
+
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - name: Set MMTk environment variables
+        run: |
+          if [[ ${{ matrix.gc.mmtk_build }} == debug ]]; then
+            echo 'RUST_LOG=' >> $GITHUB_ENV
+            # Debug builds run much slower so we should increase the timeout
+            echo 'RUBY_TEST_TIMEOUT_SCALE=10' >> $GITHUB_ENV
+            # SYNTAX_SUGGEST_TIMEOUT defaults to 1 second
+            echo 'SYNTAX_SUGGEST_TIMEOUT=60' >> $GITHUB_ENV
+          fi
+          echo 'MMTK_PLAN=${{ matrix.gc.mmtk_plan }}' >> $GITHUB_ENV
+          echo 'EXCLUDES=../src/test/.excludes-mmtk' >> $GITHUB_ENV
+          echo 'MSPECOPT=-B../src/spec/mmtk.mspec' >> $GITHUB_ENV
+        if: ${{ matrix.gc.name == 'mmtk' }}
+
+      - run: $SETARCH make
+
+      - name: Build Modular  GC
+        run: |
+          echo "RUBY_GC_LIBRARY=${{ matrix.gc.name }}" >> $GITHUB_ENV
+          make modular-gc MODULAR_GC=${{ matrix.gc.name }} MMTK_BUILD=${{ matrix.gc.mmtk_build }}
+          make distclean-modular-gc MODULAR_GC=${{ matrix.gc.name }}
+
+      - run: |
+          $SETARCH make golf
+          case "${{ matrix.configure }}" in
+          *'--enable-shared'*)
+            $SETARCH make runnable
+            ./bin/goruby -veh
+            ;;
+          *)
+            ./goruby -veh
+            ;;
+          esac
+
+      - name: Set test options for skipped tests
+        run: |
+          set -x
+          TESTS="$(echo "${{ matrix.skipped_tests }}" | sed 's| |$$/ -n!/|g;s|^|-n!/|;s|$|$$/|')"
+          echo "TESTS=${TESTS}" >> $GITHUB_ENV
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+
+      - name: Set up Launchable
+        uses: ./.github/actions/launchable/setup
+        with:
+          os: ${{ matrix.os || 'ubuntu-22.04' }}
+          test-opts: ${{ matrix.configure }}
+          launchable-token: ${{ secrets.LAUNCHABLE_TOKEN }}
+          builddir: build
+          srcdir: src
+        continue-on-error: true
+
+      - name: make ${{ matrix.test_task }}
+        run: >-
+          $SETARCH make -s ${{ matrix.test_task }}
+          ${TESTS:+TESTS="$TESTS"}
+          ${{ !contains(matrix.test_task, 'bundle') && 'RUBYOPT=-w' || '' }}
+        timeout-minutes: ${{ matrix.gc.timeout || 40 }}
+        env:
+          RUBY_TESTOPTS: '-q --tty=no'
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: 'typeprof'
+          PRECHECK_BUNDLED_GEMS: 'no'
+
+      - name: make skipped tests
+        run: |
+          $SETARCH make -s test-all TESTS="${TESTS//-n!\//-n/}"
+        env:
+          GNUMAKEFLAGS: ''
+          RUBY_TESTOPTS: '-v --tty=no'
+        if: ${{ matrix.test_task == 'check' && matrix.skipped_tests }}
+        continue-on-error: ${{ matrix.continue-on-skipped_tests || false }}
+
+      - uses: ./.github/actions/slack
+        with:
+          label: ${{ matrix.test_task }} ${{ matrix.configure }}${{ matrix.arch }}
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() }}
+
+  result:
+    if: ${{ always() }}
+    name: ${{ github.workflow }} result
+    runs-on: ubuntu-latest
+    needs: [check]
+    steps:
+      - run: exit 1
+        working-directory:
+        if: ${{ contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled') }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/common.mk b/common.mk
index 8dd1f1660c..275b1fbde8 100644
--- a/common.mk
+++ b/common.mk
@@ -753,6 +753,7 @@ clean-extout: PHONY
 	-$(Q)$(RMDIR) $(EXTOUT)/$(arch) $(RUBYCOMMONDIR) $(EXTOUT) 2> $(NULL) || $(NULLCMD)
 clean-gc: PHONY
 	$(Q) $(RMALL) .gc
+	$(Q) $(RMALL) gc
 clean-docs: clean-rdoc clean-html clean-capi
 clean-spec: PHONY
 clean-rubyspec: clean-spec
@@ -1960,7 +1961,7 @@ clean-modular-gc:
 	- $(CHDIR) gc/$(MODULAR_GC) && $(exec) $(MAKE) TARGET_SO_DIR=./ clean || $(NULLCMD)
 distclean-modular-gc: clean-modular-gc
 	- $(CHDIR) gc/$(MODULAR_GC) && $(exec) $(MAKE) TARGET_SO_DIR=./ distclean || $(NULLCMD)
-	$(RMDIRS) gc/$(MODULAR_GC)
+	$(RMALL) gc/$(MODULAR_GC)
 
 help: PHONY
 	$(MESSAGE_BEGIN) \