diff --git a/.github/workflows/MacOS.yml b/.github/workflows/MacOS.yml
index 1e067913..bd85cdb5 100644
--- a/.github/workflows/MacOS.yml
+++ b/.github/workflows/MacOS.yml
@@ -44,22 +44,22 @@ jobs:
             cling-version: '1.2'
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host;NVPTX"
-          - name: osx13-x86-clang-clang-repl-19
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-19
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '19'
             cling: Off
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host"
-          - name: osx13-x86-clang-clang-repl-18
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-18
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '18'
             cling: Off
             llvm_enable_projects: "clang"
             llvm_targets_to_build: "host"
-          - name: osx13-x86-clang-clang18-cling
-            os: macos-13
+          - name: osx15-x86-clang-clang18-cling
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '18'
             cling: On
@@ -125,28 +125,13 @@ jobs:
           echo "CC=gcc-${vers}" >> $GITHUB_ENV
           echo "CXX=g++-${vers}" >> $GITHUB_ENV
         else
-          export ARCHITECHURE=$(uname -m)
-          if [[ "$ARCHITECHURE" == "arm64" ]]; then
-            cling_on=$(echo "${{ matrix.cling }}" | tr '[:lower:]' '[:upper:]')
-            if [[ "${cling_on}" == "ON" ]]; then  
-                brew install llvm@15
-                brew remove llvm@18
-                brew cleanup
-                #FIXME: Do not believe setting all these environment variables are necessary
-                #       They were set to avoid using Xcodes libc++ and to stop CppInterOp using llvm@18 in tests
-                echo 'LDFLAGS="-L/opt/homebrew/opt/llvm@15/lib/ -L/opt/homebrew/opt/llvm@15/c++/"' >> $GITHUB_ENV
-                echo 'CPPFLAGS="-I/opt/homebrew/opt/llvm@15/include"' >> $GITHUB_ENV
-                echo 'CPATH="/opt/homebrew/include/"' >> $GITHUB_ENV
-                echo 'LIBRARY_PATH="/opt/homebrew/lib/"' >> $GITHUB_ENV
-                echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-                echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
-            else
-              echo "CC=$(brew --prefix llvm@18)/bin/clang" >> $GITHUB_ENV
-              echo "CXX=$(brew --prefix llvm@18)/bin/clang++" >> $GITHUB_ENV
-            fi
+          brew install llvm@15
+          if [[ "$(uname -m)" == "x86_64" ]]; then
+            echo "CC=/usr/local/opt/llvm@15/bin/clang" >> $GITHUB_ENV
+            echo "CXX=/usr/local/opt/llvm@15/bin/clang++" >> $GITHUB_ENV
           else
-            echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-            echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
+            echo "CC=/opt/homebrew/opt/llvm@15/bin/clang" >> $GITHUB_ENV
+            echo "CXX=/opt/homebrew/opt/llvm@15/bin/clang++" >> $GITHUB_ENV
           fi
         fi
         echo "SDKROOT=$(xcrun --sdk macosx --show-sdk-path)" >> $GITHUB_ENV
@@ -284,20 +269,20 @@ jobs:
             cling: On
             cling-version: '1.2'
             cppyy: On
-          - name: osx13-x86-clang-clang-repl-19-cppyy
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-19-cppyy
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '19'
             cling: Off
             cppyy: On
-          - name: osx13-x86-clang-clang-repl-18-cppyy
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-18-cppyy
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '18'
             cling: Off
             cppyy: On
-          - name: osx13-x86-clang-clang18-cling-cppyy
-            os: macos-13
+          - name: osx15-x86-clang-clang18-cling-cppyy
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '18'
             cling: On
@@ -366,31 +351,16 @@ jobs:
           echo "CC=gcc-${vers}" >> $GITHUB_ENV
           echo "CXX=g++-${vers}" >> $GITHUB_ENV
         else
-          echo "SDKROOT=$(xcrun --sdk macosx --show-sdk-path)" >> $GITHUB_ENV
-          export ARCHITECHURE=$(uname -m)
-          if [[ "$ARCHITECHURE" == "arm64" ]]; then
-            cling_on=$(echo "${{ matrix.cling }}" | tr '[:lower:]' '[:upper:]')
-            if [[ "${cling_on}" == "ON" ]]; then  
-                brew install llvm@15
-                brew remove llvm@18
-                brew cleanup
-                #FIXME: Do not believe setting all these environment variables are necessary
-                #       They were set to avoid using Xcodes libc++ and to stop CppInterOp using llvm@18 in tests
-                echo 'LDFLAGS="-L/opt/homebrew/opt/llvm@15/lib/ -L/opt/homebrew/opt/llvm@15/c++/"' >> $GITHUB_ENV
-                echo 'CPPFLAGS="-I/opt/homebrew/opt/llvm@15/include"' >> $GITHUB_ENV
-                echo 'CPATH="/opt/homebrew/include/"' >> $GITHUB_ENV
-                echo 'LIBRARY_PATH="/opt/homebrew/lib/"' >> $GITHUB_ENV
-                echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-                echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
-            else
-              echo "CC=$(brew --prefix llvm@18)/bin/clang" >> $GITHUB_ENV
-              echo "CXX=$(brew --prefix llvm@18)/bin/clang++" >> $GITHUB_ENV
-            fi
+          brew install llvm@15
+          if [[ "$(uname -m)" == "x86_64" ]]; then
+            echo "CC=/usr/local/opt/llvm@15/bin/clang" >> $GITHUB_ENV
+            echo "CXX=/usr/local/opt/llvm@15/bin/clang++" >> $GITHUB_ENV
           else
-            echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-            echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
+            echo "CC=/opt/homebrew/opt/llvm@15/bin/clang" >> $GITHUB_ENV
+            echo "CXX=/opt/homebrew/opt/llvm@15/bin/clang++" >> $GITHUB_ENV
           fi
         fi
+        echo "SDKROOT=$(xcrun --sdk macosx --show-sdk-path)" >> $GITHUB_ENV
       env:
         compiler: ${{ matrix.compiler }}
 
diff --git a/.github/workflows/emscripten.yml b/.github/workflows/emscripten.yml
index 7c1cea02..c80130e5 100644
--- a/.github/workflows/emscripten.yml
+++ b/.github/workflows/emscripten.yml
@@ -45,8 +45,8 @@ jobs:
             llvm_enable_projects: "clang;lld"
             llvm_targets_to_build: "WebAssembly"
             emsdk_ver: "3.1.73"
-          - name: osx13-x86-clang-clang-repl-19-emscripten
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-19-emscripten
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '19'
             cling: Off
@@ -131,18 +131,6 @@ jobs:
           git clone --depth=1 https://github.com/emscripten-core/emsdk.git 
           ./emsdk/emsdk install  ${{ matrix.emsdk_ver }}
 
-    - name: Setup default Build Type on *nux
-      if: ${{ runner.os != 'windows' && steps.cache.outputs.cache-hit != 'true' }}
-      run: |
-        echo "BUILD_TYPE=Release" >> $GITHUB_ENV
-        echo "CODE_COVERAGE=0" >> $GITHUB_ENV
-        os="${{ matrix.os }}"
-        if [[ "${os}" == "macos"* ]]; then
-          echo "ncpus=$(sysctl -n hw.ncpu)" >> $GITHUB_ENV
-        else
-          echo "ncpus=$(nproc --all)" >> $GITHUB_ENV
-        fi
-
     - name: Setup default Build Type on Windows
       if: ${{ runner.os == 'windows' && steps.cache.outputs.cache-hit != 'true' }}
       run: |
@@ -151,97 +139,12 @@ jobs:
         $env:ncpus=$([Environment]::ProcessorCount) 
         echo "ncpus=$env:ncpus" >> $env:GITHUB_ENV
 
-    - name: Setup compiler on Linux
-      if: ${{ runner.os == 'Linux' && steps.cache.outputs.cache-hit != 'true' }}
-      run: |
-        # https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
-        vers="${compiler#*-}"
-        os_codename="`cat /etc/os-release | grep UBUNTU_CODENAME | cut -d = -f 2`"
-        ##sudo apt update
-        if [[ "${{ matrix.compiler }}" == *"gcc"* ]]; then
-          sudo apt install -y gcc-${vers} g++-${vers} lld
-          echo "CC=gcc-${vers}" >> $GITHUB_ENV
-          echo "CXX=g++-${vers}" >> $GITHUB_ENV
-        else
-          if ! sudo apt install -y clang-${vers}; then
-            curl https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-            echo "deb https://apt.llvm.org/${os_codename}/ llvm-toolchain-${os_codename}-${vers} main" | sudo tee -a /etc/apt/sources.list
-            sudo apt-get update
-            sudo apt-get install -y clang-${vers}
-          fi
-          echo "CC=clang-${vers}" >> $GITHUB_ENV
-          echo "CXX=clang++-${vers}" >> $GITHUB_ENV
-        fi
-      env:
-        compiler: ${{ matrix.compiler }}
-
-    - name: Setup compiler on macOS
-      if: ${{ runner.os == 'macOS' && steps.cache.outputs.cache-hit != 'true' }}
-      run: |
-        vers="${compiler#*-}"
-        if [[ "${{ matrix.compiler }}" == *"gcc"* ]]; then
-          brew install "gcc@$vers"
-          echo "CC=gcc-${vers}" >> $GITHUB_ENV
-          echo "CXX=g++-${vers}" >> $GITHUB_ENV
-        else
-          export ARCHITECHURE=$(uname -m)
-          if [[ "$ARCHITECHURE" == "arm64" ]]; then
-            cling_on=$(echo "${{ matrix.cling }}" | tr '[:lower:]' '[:upper:]')
-            if [[ "${cling_on}" == "ON" ]]; then  
-                brew install llvm@15
-                brew remove llvm@18
-                brew cleanup
-                #FIXME: Do not believe setting all these environment variables are necessary
-                #       They were set to avoid using Xcodes libc++ and to stop CppInterOp using llvm@18 in tests
-                echo 'LDFLAGS="-L/opt/homebrew/opt/llvm@15/lib/ -L/opt/homebrew/opt/llvm@15/c++/"' >> $GITHUB_ENV
-                echo 'CPPFLAGS="-I/opt/homebrew/opt/llvm@15/include"' >> $GITHUB_ENV
-                echo 'CPATH="/opt/homebrew/include/"' >> $GITHUB_ENV
-                echo 'LIBRARY_PATH="/opt/homebrew/lib/"' >> $GITHUB_ENV
-                echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-                echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
-            else
-              echo "CC=$(brew --prefix llvm@18)/bin/clang" >> $GITHUB_ENV
-              echo "CXX=$(brew --prefix llvm@18)/bin/clang++" >> $GITHUB_ENV
-            fi
-          else
-            echo "CC=$(brew --prefix llvm@15)/bin/clang" >> $GITHUB_ENV
-            echo "CXX=$(brew --prefix llvm@15)/bin/clang++" >> $GITHUB_ENV
-          fi
-        fi
-        echo "SDKROOT=$(xcrun --sdk macosx --show-sdk-path)" >> $GITHUB_ENV
-      env:
-        compiler: ${{ matrix.compiler }}
-        
-    #Section slightly modified version of
-    #https://github.com/vgvassilev/clad/blob/40d8bec11bde47b14a281078183a4f6147abeac5/.github/workflows/ci.yml#L510C1-L534C10
-    - name: Setup compiler on Windows
-      if: ${{ runner.os == 'windows' && steps.cache.outputs.cache-hit != 'true' }}
-      run: |
-        if ( "${{ matrix.compiler }}" -imatch "clang" )
-        {
-          $ver="${{ matrix.compiler }}".split("-")[1]
-          choco install llvm --version=$ver --no-progress -my
-          clang --version
-          #
-          $env:CC="clang"
-          $env:CXX="clang++"
-          echo "CC=clang" >> $env:GITHUB_ENV
-          echo "CXX=clang++" >> $env:GITHUB_ENV
-        }
-        elseif ( "${{ matrix.compiler }}" -imatch "msvc" )
-        {
-          # MSVC is builtin in container image
-        }
-        else
-        {
-          echo "Unsupported compiler - fix YAML file"
-        }
-
     - name: Install deps on Windows
       if: ${{ runner.os == 'windows' && steps.cache.outputs.cache-hit != 'true' }}
       run: |
-        choco install findutils
+        choco install findutils ninja
         $env:PATH="C:\Program Files (x86)\GnuWin32\bin;$env:PATH"
+        $env:PATH="C:\Program Files (x86)\Ninja\bin;$env:PATH"
 
     - name: Install deps on MacOS
       if: ${{ runner.os == 'macOS' && steps.cache.outputs.cache-hit != 'true' }}
@@ -250,17 +153,13 @@ jobs:
         export ARCHITECHURE=$(uname -m)
         if [[ "$ARCHITECHURE" != "x86_64" ]]; then
           brew remove unxip
-        else
-          brew remove ruby@3.0
         fi
         # workaround for https://github.com/actions/setup-python/issues/577
         for pkg in $(brew list | grep '^python@'); do
           brew unlink "$pkg"
           brew link --overwrite "$pkg"
         done
-        brew upgrade openssl >/dev/null 2>&1 
         brew install ninja
-        brew upgrade
 
     - name: Install deps on Linux
       if: ${{ runner.os == 'Linux' && steps.cache.outputs.cache-hit != 'true' }}
@@ -281,7 +180,6 @@ jobs:
           git clone https://github.com/root-project/cling.git
           cd ./cling 
           git checkout tags/v${{ matrix.cling-version }}
-          git apply -v ${{ github.workspace }}/CppInterOp/patches/llvm/cling1.2-LookupHelper.patch
           cd ..
           git clone --depth=1 -b cling-llvm${{ matrix.clang-runtime }} https://github.com/root-project/llvm-project.git
         else # repl
@@ -289,6 +187,12 @@ jobs:
         fi
         cd llvm-project
         # Build
+        mkdir native_build
+        cd native_build
+        cmake -DLLVM_ENABLE_PROJECTS=clang -DLLVM_TARGETS_TO_BUILD=host -DCMAKE_BUILD_TYPE=Release ../llvm/
+        cmake --build . --target llvm-tblgen clang-tblgen --parallel $(nproc --all)
+        export NATIVE_DIR=$PWD/bin/
+        cd ..
         mkdir build
         if [[ "${cling_on}" == "ON" ]]; then
           cd build
@@ -316,14 +220,13 @@ jobs:
         else
           # Apply patches
           llvm_vers=$(echo "${{ matrix.clang-runtime }}" | tr '[:lower:]' '[:upper:]')
-          if [[ "${llvm_vers}" == "19" ]]; then
+          if [[ "${llvm_vers}" == "19" || "${llvm_vers}" == "20" ]]; then
             git apply -v ${{ github.workspace }}/CppInterOp/patches/llvm/emscripten-clang${{ matrix.clang-runtime }}-*.patch
             echo "Apply emscripten-clang${{ matrix.clang-runtime }}-*.patch patches:"
           fi
           cd build
           emcmake cmake -DCMAKE_BUILD_TYPE=Release \
                         -DLLVM_HOST_TRIPLE=wasm32-unknown-emscripten \
-                        -DLLVM_ENABLE_ASSERTIONS=ON                        \
                         -DLLVM_TARGETS_TO_BUILD="${{ matrix.llvm_targets_to_build }}" \
                         -DLLVM_ENABLE_LIBEDIT=OFF \
                         -DLLVM_ENABLE_PROJECTS="${{ matrix.llvm_enable_projects }}" \
@@ -337,9 +240,16 @@ jobs:
                         -DLLVM_INCLUDE_EXAMPLES=OFF                     \
                         -DLLVM_INCLUDE_TESTS=OFF                        \
                         -DLLVM_ENABLE_THREADS=OFF                       \
+                        -DLLVM_BUILD_TOOLS=OFF                          \
+                        -DLLVM_ENABLE_LIBPFM=OFF                        \
+                        -DCLANG_BUILD_TOOLS=OFF                         \
                         -G Ninja                                         \
+                        -DLLVM_NATIVE_TOOL_DIR=$NATIVE_DIR 		\
+                        -DCMAKE_C_FLAGS_RELEASE="-Oz -g0 -DNDEBUG" \
+                        -DCMAKE_CXX_FLAGS_RELEASE="-Oz -g0 -DNDEBUG" \
+                        -DLLVM_ENABLE_LTO=Full \
                         ../llvm
-          emmake ninja clang clang-repl lld -j ${{ env.ncpus }}
+          emmake ninja libclang clangInterpreter clangStaticAnalyzerCore lldWasm
         fi
         cd ../
         rm -rf $(find . -maxdepth 1 ! -name "build" ! -name "llvm" ! -name "clang" ! -name ".")
@@ -489,8 +399,8 @@ jobs:
             cling: Off
             micromamba_shell_init: bash
             emsdk_ver: "3.1.73"
-          - name: osx13-x86-clang-clang-repl-19-emscripten_wasm
-            os: macos-13
+          - name: osx15-x86-clang-clang-repl-19-emscripten_wasm
+            os: macos-15-intel
             compiler: clang
             clang-runtime: '19'
             cling: Off