diff --git a/.ci/monolithic-macos.sh b/.ci/monolithic-macos.sh
new file mode 100755
index 000000000000..3656fa331193
--- /dev/null
+++ b/.ci/monolithic-macos.sh
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+#===----------------------------------------------------------------------===##
+#
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+#===----------------------------------------------------------------------===##
+
+#
+# This script performs a monolithic build of the monorepo and runs the tests of
+# most projects on macOS.
+#
+
+source .ci/utils.sh
+
+projects="${1}"
+targets="${2}"
+runtimes="${3}"
+runtime_targets="${4}"
+
+start-group "CMake"
+
+xcrun cmake -G Ninja \
+      -B "${BUILD_DIR}" \
+      -S "${MONOREPO_ROOT}"/llvm \
+      -D LLVM_ENABLE_PROJECTS="${projects}" \
+      -D LLVM_ENABLE_RUNTIMES="${runtimes}" \
+      -D LLVM_DISABLE_ASSEMBLY_FILES=ON \
+      -D CMAKE_BUILD_TYPE=Release \
+      -D LLDB_INCLUDE_TESTS=OFF \
+      -D LLVM_ENABLE_ASSERTIONS=ON \
+      -D Python3_EXECUTABLE="${RUNNER_TEMP}/venv/bin/python3" \
+      -D LLVM_LIT_ARGS="-v --xunit-xml-output ${BUILD_DIR}/test-results.xml --use-unique-output-file-name --timeout=1200 --time-tests --succinct" \
+      -D CMAKE_C_COMPILER_LAUNCHER=sccache \
+      -D CMAKE_CXX_COMPILER_LAUNCHER=sccache
+
+start-group "ninja"
+
+if [[ -n "${targets}" ]]; then
+  ninja -C "${BUILD_DIR}" ${targets} 2>&1 | tee ninja.log
+  cp ${BUILD_DIR}/.ninja_log ninja.ninja_log
+fi
+
+if [[ -n "${runtime_targets}" ]]; then
+  start-group "ninja Runtimes"
+
+  ninja -C "${BUILD_DIR}" ${runtime_targets} 2>&1 | tee ninja_runtimes.log
+  cp ${BUILD_DIR}/.ninja_log ninja_runtimes.ninja_log
+fi
diff --git a/.github/workflows/premerge.yaml b/.github/workflows/premerge.yaml
index 9d1329eea434..8c8d63fb5bec 100644
--- a/.github/workflows/premerge.yaml
+++ b/.github/workflows/premerge.yaml
@@ -286,6 +286,10 @@ jobs:
         run: |
           brew install ninja cmake
           command -v sccache >/dev/null || brew install sccache
+      - name: Set up Python venv
+        run: |
+          "$(brew --prefix python@3.14)/bin/python3.14" -m venv "${RUNNER_TEMP}/venv"
+          echo "${RUNNER_TEMP}/venv/bin" >> "$GITHUB_PATH"
       - name: Build and Test
         timeout-minutes: 240
         env:
@@ -296,34 +300,14 @@ jobs:
           RUNTIMES: ${{ needs.premerge-compute-macos.outputs.macos-runtimes }}
           RUNTIMES_CHECK_TARGETS: ${{ needs.premerge-compute-macos.outputs.macos-runtimes-check-targets }}
           CLANG_TOOLCHAIN_PROGRAM_TIMEOUT: 120
+          GITHUB_TOKEN: ${{ github.token }}
+          GITHUB_PR_NUMBER: ${{ github.event.pull_request.number }}
         run: |
           export SCCACHE_IDLE_TIMEOUT=0
           mkdir -p artifacts
           SCCACHE_LOG=info SCCACHE_ERROR_LOG=$(pwd)/artifacts/sccache.log sccache --start-server
 
-          xcrun cmake -G Ninja \
-                -B build \
-                -S llvm \
-                -DLLVM_ENABLE_PROJECTS="${PROJECTS}" \
-                -DLLVM_ENABLE_RUNTIMES="${RUNTIMES}" \
-                -DLLVM_DISABLE_ASSEMBLY_FILES=ON \
-                -DCMAKE_BUILD_TYPE=Release \
-                -DLLDB_INCLUDE_TESTS=OFF \
-                -DLLVM_ENABLE_ASSERTIONS=ON \
-                -DCMAKE_C_COMPILER_LAUNCHER=sccache \
-                -DCMAKE_CXX_COMPILER_LAUNCHER=sccache
-
-          ninja -C build ${CHECK_TARGETS}
-
-          if [[ -n "${RUNTIMES_CHECK_TARGETS}" ]]; then
-            ninja -C build ${RUNTIMES_CHECK_TARGETS}
-          fi
-      - name: Show sccache stats
-        if: always()
-        run: |
-          mkdir -p artifacts
-          sccache --show-stats
-          sccache --show-stats >> artifacts/sccache_stats.txt
+          ./.ci/monolithic-macos.sh "${PROJECTS}" "${CHECK_TARGETS}" "${RUNTIMES}" "${RUNTIMES_CHECK_TARGETS}"
       - name: Upload Artifacts
         # In some cases, Github will fail to upload the artifact. We want to
         # continue anyways as a failed artifact upload is an infra failure, not