diff --git a/.github/workflows/compilers.yml b/.github/workflows/compilers.yml
index 6ddfba05db..e6ad9db6e2 100644
--- a/.github/workflows/compilers.yml
+++ b/.github/workflows/compilers.yml
@@ -167,6 +167,7 @@ jobs:
 #         - { key: cppflags, name: VM_DEBUG_VERIFY_METHOD_CACHE,   value: '-DVM_DEBUG_VERIFY_METHOD_CACHE' }
 
           - { key: cppflags, name: MJIT_FORCE_ENABLE,              value: '-DMJIT_FORCE_ENABLE' }
+          - { key: cppflags, name: YJIT_FORCE_ENABLE,              value: '-DYJIT_FORCE_ENABLE' }
 
     name: ${{ matrix.entry.name }}
     runs-on: ubuntu-latest
diff --git a/.github/workflows/yjit-macos.yml b/.github/workflows/yjit-macos.yml
new file mode 100644
index 0000000000..be0f3c8986
--- /dev/null
+++ b/.github/workflows/yjit-macos.yml
@@ -0,0 +1,69 @@
+name: YJIT MacOS
+on: [push, pull_request]
+jobs:
+  make:
+    runs-on: macos-latest
+    strategy:
+      matrix:
+        test_task: [ "check", "test-bundler-parallel" ] #, "test-bundled-gems" ]
+        yjit_opts: [
+          "--yjit",
+          "--yjit --yjit-call-threshold=1 --yjit-max-versions=1",
+          "--yjit --yjit-call-threshold=1",
+          "--yjit --yjit-call-threshold=2"
+        ]
+      fail-fast: false
+    env:
+      TESTOPTS: '-q --tty=no'
+      RUN_OPTS: '--disable-gems ${{ matrix.yjit_opts }}'
+      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+    steps:
+      - run: mkdir build
+        working-directory:
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@v2
+        with:
+          path: src
+      - name: Install libraries
+        run: |
+          brew upgrade
+          brew install gmp libffi openssl@1.1 zlib autoconf automake libtool readline
+        working-directory: src
+      - name: Set ENV
+        run: |
+          echo "JOBS=-j$((1 + $(sysctl -n hw.activecpu)))" >> $GITHUB_ENV
+      - run: ./autogen.sh
+        working-directory: src
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc --with-openssl-dir=$(brew --prefix openssl@1.1) --with-readline-dir=$(brew --prefix readline)
+      - run: make $JOBS incs
+      - run: make $JOBS
+#      - run: make leaked-globals
+#      if: matrix.test_task == 'check'
+      - run: make prepare-gems
+        if: ${{ matrix.test_task == 'check' }}
+      - run: make $JOBS -s ${{ matrix.test_task }}
+        timeout-minutes: 60
+        env:
+          RUBY_TESTOPTS: "-q --tty=no"
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: "rexml"
+      - uses: k0kubun/action-slack@v2.0.0
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ github.workflow }} / ${{ matrix.test_task }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref }}".split('/').reverse()[0]
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/yjit-ubuntu.yml b/.github/workflows/yjit-ubuntu.yml
new file mode 100644
index 0000000000..93e12b725f
--- /dev/null
+++ b/.github/workflows/yjit-ubuntu.yml
@@ -0,0 +1,86 @@
+name: Ubuntu
+on: [push, pull_request]
+jobs:
+  make:
+    strategy:
+      matrix:
+        test_task: ["check", "test-bundler-parallel", "test-bundled-gems", "test-all", "test-spec"]
+        os:
+          - ubuntu-20.04
+#         - ubuntu-18.04
+        yjit_opts: [
+          "--yjit",
+          "--yjit --yjit-call-threshold=1 --yjit-max-versions=1",
+          "--yjit --yjit-call-threshold=1",
+          "--yjit --yjit-call-threshold=2"
+        ]
+        configure: ["", "cppflags=-DRUBY_DEBUG"]
+        include:
+          - test_task: "test-all TESTS=--repeat-count=2"
+            os: ubuntu-20.04
+            configure: ""
+      fail-fast: false
+    env:
+      GITPULLOPTIONS: --no-tags origin ${{github.ref}}
+      RUN_OPTS: ${{ matrix.yjit_opts }}
+      RUBY_DEBUG: ci
+    runs-on: ${{ matrix.os }}
+    steps:
+      - run: mkdir build
+        working-directory:
+      - name: Install libraries
+        run: |
+          set -x
+          sudo apt-get update -q || :
+          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev bison autoconf ruby
+      - name: git config
+        run: |
+          git config --global advice.detachedHead 0
+          git config --global init.defaultBranch garbage
+      - uses: actions/checkout@v2
+        with:
+          path: src
+      - name: Fixed world writable dirs
+        run: |
+          chmod -v go-w $HOME $HOME/.config
+          sudo chmod -R go-w /usr/share
+          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
+      - name: Set ENV
+        run: |
+          echo "JOBS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
+      - run: ./autogen.sh
+        working-directory: src
+      - name: Run configure
+        run: ../src/configure -C --disable-install-doc ${{ matrix.configure }}
+      - run: make $JOBS incs
+      - run: make $JOBS
+#      - run: make leaked-globals
+#        if: matrix.test_task == 'check'
+      - run: make prepare-gems
+        if: ${{ matrix.test_task == 'check' }}
+      - name: Create dummy files in build dir
+        run: |
+          ./miniruby -e '(("a".."z").to_a+("A".."Z").to_a+("0".."9").to_a+%w[foo bar test zzz]).each{|basename|File.write("#{basename}.rb", "raise %(do not load #{basename}.rb)")}'
+        if: ${{ matrix.test_task == 'check' }}
+      - run: make $JOBS -s ${{ matrix.test_task }} RUN_OPTS="$RUN_OPTS"
+        timeout-minutes: 60
+        env:
+          RUBY_TESTOPTS: "-q --tty=no"
+          TEST_BUNDLED_GEMS_ALLOW_FAILURES: ""
+      - uses: k0kubun/action-slack@v2.0.0
+        with:
+          payload: |
+            {
+              "ci": "GitHub Actions",
+              "env": "${{ matrix.os }} / ${{ matrix.test_task }}${{ matrix.configure }}",
+              "url": "https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}",
+              "commit": "${{ github.sha }}",
+              "branch": "${{ github.ref }}".split('/').reverse()[0]
+            }
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SIMPLER_ALERTS_URL }} # ruby-lang slack: ruby/simpler-alerts-bot
+        if: ${{ failure() && github.event_name == 'push' }}
+
+defaults:
+  run:
+    working-directory: build
diff --git a/.github/workflows/yjit.yml b/.github/workflows/yjit.yml
deleted file mode 100644
index 6263e7c533..0000000000
--- a/.github/workflows/yjit.yml
+++ /dev/null
@@ -1,70 +0,0 @@
-name: YJIT options
-on: [push, pull_request]
-jobs:
-  make:
-    strategy:
-      matrix:
-        # To make job names consistent
-        test_task: [ "check" ]
-        # Run with multiple thresholds and params to surface more bugs
-        yjit_opts: [
-          "--yjit-call-threshold=1 --yjit-max-versions=1",
-          "--yjit-call-threshold=1",
-          "--yjit-call-threshold=2"
-        ]
-      fail-fast: false
-    runs-on: ubuntu-latest
-    env:
-      TESTOPTS: '-q --tty=no'
-      RUN_OPTS: '--disable-gems ${{ matrix.yjit_opts }}'
-      GITPULLOPTIONS: --no-tags origin ${{ github.ref }}
-    steps:
-      - run: mkdir build
-        working-directory:
-      - name: Install libraries
-        run: |
-          set -x
-          sudo apt-get update -q || :
-          sudo apt-get install --no-install-recommends -q -y build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm-dev bison autoconf ruby
-      - name: git config
-        run: |
-          git config --global advice.detachedHead 0
-          git config --global init.defaultBranch garbage
-      - uses: actions/checkout@v2
-        with:
-          path: src
-      - name: Fixed world writable dirs
-        run: |
-          chmod -v go-w $HOME $HOME/.config
-          sudo chmod -R go-w /usr/share
-          sudo bash -c 'IFS=:; for d in '"$PATH"'; do chmod -v go-w $d; done' || :
-      - name: Set ENV
-        run: |
-          echo "JOBS=-j$((1 + $(nproc --all)))" >> $GITHUB_ENV
-      - run: ./autogen.sh
-        working-directory: src
-      - name: Run configure
-        run: ../src/configure -C --disable-install-doc
-      - run: make $JOBS incs
-      - run: make $JOBS
-      - run: sudo make $JOBS -s install
-      - run: sudo apt-get install gdb # used by test / test-all failure
-      - name: Run test
-        run: |
-          ulimit -c unlimited
-          make $JOBS -s test RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-      - name: Run test-all
-        run: |
-          ulimit -c unlimited
-          make $JOBS -s test-all RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-      - name: Run test-spec
-        run: |
-          ulimit -c unlimited
-          make $JOBS -s test-spec RUN_OPTS="$RUN_OPTS"
-        timeout-minutes: 60
-
-defaults:
-  run:
-    working-directory: build
diff --git a/ruby.c b/ruby.c
index 6895838f5e..0476135d34 100644
--- a/ruby.c
+++ b/ruby.c
@@ -234,9 +234,14 @@ cmdline_options_init(ruby_cmdline_options_t *opt)
     opt->features.set = DEFAULT_FEATURES;
 #ifdef MJIT_FORCE_ENABLE /* to use with: ./configure cppflags="-DMJIT_FORCE_ENABLE" */
     opt->features.set |= FEATURE_BIT(jit);
-#else
+#elif defined(YJIT_FORCE_ENABLE)
     opt->features.set |= FEATURE_BIT(yjit);
 #endif
+
+    if(getenv("RUBY_YJIT_ENABLE")) {
+        opt->features.set |= FEATURE_BIT(yjit);
+    }
+
     return opt;
 }
 
diff --git a/yjit_iface.c b/yjit_iface.c
index afeb9178e6..73b51fd50d 100644
--- a/yjit_iface.c
+++ b/yjit_iface.c
@@ -1092,7 +1092,7 @@ rb_yjit_init(struct rb_yjit_options *options)
     rb_yjit_opts = *options;
     rb_yjit_opts.yjit_enabled = true;
 
-    rb_yjit_opts.gen_stats |= !!getenv("YJIT_STATS");
+    rb_yjit_opts.gen_stats = rb_yjit_opts.gen_stats || getenv("RUBY_YJIT_STATS");
 
 #if !YJIT_STATS
     if(rb_yjit_opts.gen_stats) {