diff --git a/.kokoro/presubmit/linux/presubmit-linux.cfg b/.kokoro/presubmit/linux/presubmit-linux.cfg
index ee331e079f5d..a725ad012410 100644
--- a/.kokoro/presubmit/linux/presubmit-linux.cfg
+++ b/.kokoro/presubmit/linux/presubmit-linux.cfg
@@ -6,6 +6,4 @@ action {
     regex: "**/*sponge_log.xml"
   }
 }
-
-# Bypass the trampoline entirely and run our dummy script natively
-build_file: "google-cloud-python/packages/google-crc32c/scripts/bypass.sh"
\ No newline at end of file
+build_file: "google-cloud-python/packages/google-crc32c/scripts/manylinux/build.sh"
\ No newline at end of file
diff --git a/.kokoro/presubmit/osx/presubmit-osx-slcn.cfg b/.kokoro/presubmit/osx/presubmit-osx-slcn.cfg
index b0d3c471cc53..fc516d14c7bf 100644
--- a/.kokoro/presubmit/osx/presubmit-osx-slcn.cfg
+++ b/.kokoro/presubmit/osx/presubmit-osx-slcn.cfg
@@ -7,5 +7,4 @@ action {
   }
 }
 
-# Reuse the exact same bash script we used for Linux!
-build_file: "google-cloud-python/packages/google-crc32c/scripts/bypass.sh"
\ No newline at end of file
+build_file: "google-cloud-python/packages/google-crc32c/scripts/osx/build.sh"
\ No newline at end of file
diff --git a/.kokoro/presubmit/osx/presubmit-osx.cfg b/.kokoro/presubmit/osx/presubmit-osx.cfg
index b0d3c471cc53..fc516d14c7bf 100644
--- a/.kokoro/presubmit/osx/presubmit-osx.cfg
+++ b/.kokoro/presubmit/osx/presubmit-osx.cfg
@@ -7,5 +7,4 @@ action {
   }
 }
 
-# Reuse the exact same bash script we used for Linux!
-build_file: "google-cloud-python/packages/google-crc32c/scripts/bypass.sh"
\ No newline at end of file
+build_file: "google-cloud-python/packages/google-crc32c/scripts/osx/build.sh"
\ No newline at end of file
diff --git a/.kokoro/presubmit/windows/presubmit-windows-google-crc32c.cfg b/.kokoro/presubmit/windows/presubmit-windows-google-crc32c.cfg
index ebcd16aba79e..9eb3fc4e0edb 100644
--- a/.kokoro/presubmit/windows/presubmit-windows-google-crc32c.cfg
+++ b/.kokoro/presubmit/windows/presubmit-windows-google-crc32c.cfg
@@ -7,5 +7,4 @@ action {
   }
 }
 
-# Reuse the exact same bash script we used for Linux!
-build_file: "google-cloud-python/packages/google-crc32c/scripts/bypass.bat"
\ No newline at end of file
+build_file: "google-cloud-python/packages/google-crc32c/scripts/windows/build.bat"
\ No newline at end of file
diff --git a/packages/google-crc32c/scripts/bypass.bat b/packages/google-crc32c/scripts/bypass.bat
deleted file mode 100644
index 9cd005f6290c..000000000000
--- a/packages/google-crc32c/scripts/bypass.bat
+++ /dev/null
@@ -1,7 +0,0 @@
-@echo off
-echo Bypassing C-extension tests for Phase 1 migration.
-
-:: Generate the dummy sponge log so Kokoro parses a green checkmark
-echo ^<?xml version="1.0" encoding="UTF-8"?^>^<testsuites^>^<testsuite name="bypass" tests="1" failures="0" errors="0"^>^<testcase name="migration_bypass" classname="bypass"/^>^</testsuite^>^</testsuites^> > sponge_log.xml
-
-exit /b 0
\ No newline at end of file
diff --git a/packages/google-crc32c/scripts/bypass.sh b/packages/google-crc32c/scripts/bypass.sh
deleted file mode 100644
index 720f3017f94f..000000000000
--- a/packages/google-crc32c/scripts/bypass.sh
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/bin/bash
-
-# 1. Print a message to the raw Kokoro build log
-echo "Bypassing C-extension tests for Phase 1 migration."
-echo "Tests will be wired into internal infrastructure in a follow-up PR."
-
-# 2. Generate a fake Sponge Log so Kokoro doesn't throw a 404 error
-echo '<?xml version="1.0" encoding="UTF-8"?><testsuites><testsuite name="bypass" tests="1" failures="0" errors="0"><testcase name="migration_bypass" classname="bypass"/></testsuite></testsuites>' > sponge_log.xml
-
-# 3. Exit successfully
-exit 0
\ No newline at end of file
diff --git a/packages/google-crc32c/scripts/manylinux/build.sh b/packages/google-crc32c/scripts/manylinux/build.sh
index 91397c8eba00..484e2a4160c8 100755
--- a/packages/google-crc32c/scripts/manylinux/build.sh
+++ b/packages/google-crc32c/scripts/manylinux/build.sh
@@ -28,8 +28,7 @@ sudo apt-get install -y python3.12
 
 cd $REPO_ROOT
 # Add directory as safe to avoid "detected dubious ownership" fatal issue1
-git config --global --add safe.directory $REPO_ROOT
-git config --global --add safe.directory $REPO_ROOT/google_crc32c
+git config --global --add safe.directory '*'
 git submodule update --init --recursive
 
 
diff --git a/packages/google-crc32c/scripts/osx/build.sh b/packages/google-crc32c/scripts/osx/build.sh
index 7000337c70b4..075ffcc26193 100755
--- a/packages/google-crc32c/scripts/osx/build.sh
+++ b/packages/google-crc32c/scripts/osx/build.sh
@@ -32,8 +32,7 @@ export CRC32C_INSTALL_PREFIX="${REPO_ROOT}/usr"
 
 cd ${REPO_ROOT}
 # Add directory as safe to avoid "detected dubious ownership" fatal issue
-git config --global --add safe.directory $REPO_ROOT
-git config --global --add safe.directory $REPO_ROOT/google_crc32c
+git config --global --add safe.directory '*'
 git submodule update --init --recursive
 
 ${OSX_DIR}/build_c_lib.sh
diff --git a/packages/google-crc32c/scripts/osx/build_python_wheel.sh b/packages/google-crc32c/scripts/osx/build_python_wheel.sh
index c63241677364..1695a1595eb1 100755
--- a/packages/google-crc32c/scripts/osx/build_python_wheel.sh
+++ b/packages/google-crc32c/scripts/osx/build_python_wheel.sh
@@ -52,12 +52,8 @@ install_python_pyenv() {
 install_python_pyenv ${PY_BIN}
 
 
-# ``readlink -f`` is not our friend on OS X. This relies on **some**
-# ``python`` being installed.
-SCRIPT_FI=$(python3 -c "import os; print(os.path.realpath('${0}'))")
-OSX_DIR=$(dirname ${SCRIPT_FI})
-SCRIPTS_DIR=$(dirname ${OSX_DIR})
-export REPO_ROOT=$(dirname ${SCRIPTS_DIR})
+# Rely on the REPO_ROOT already provided by the parent script
+OSX_DIR="${REPO_ROOT}/scripts/osx"
 
 # Create a virtualenv where we can install Python build dependencies.
 VENV=${REPO_ROOT}/venv${PY_BIN}
diff --git a/packages/google-crc32c/scripts/windows/build.bat b/packages/google-crc32c/scripts/windows/build.bat
index c2b6b6fcb779..3757d911d4ce 100644
--- a/packages/google-crc32c/scripts/windows/build.bat
+++ b/packages/google-crc32c/scripts/windows/build.bat
@@ -40,12 +40,8 @@ FOR %%P IN (3.9, 3.10, 3.11, 3.12, 3.13.1, 3.14.0) DO (
     py -!python_version_trimmed!-64 -m pip install cmake
 
     @rem Add directory as safe to avoid "detected dubious ownership" fatal issue
-    git config --global --add safe.directory %cd%
-    git config --global --add safe.directory C:/tmpfs/src/github/python-crc32c
+    git config --global --add safe.directory *
     git submodule update --init --recursive
-
-    git config --global --add safe.directory %cd%\google_crc32c
-    git config --global --add safe.directory C:/tmpfs/src/github/python-crc32c/google_crc32c
     pushd google_crc32c
     @rem reset hard to cleanup any changes done by a previous build.
     git reset --hard
@@ -59,7 +55,7 @@ FOR %%P IN (3.9, 3.10, 3.11, 3.12, 3.13.1, 3.14.0) DO (
 
     echo "Running cmake with Generator:  %CMAKE_GENERATOR%, Platform: x64, Install Prefix: %CRC32C_INSTALL_PREFIX%"
 
-    py -!python_version_trimmed!-64 -m cmake -G "Visual Studio 17 2022" -A x64 -DCMAKE_POLICY_VERSION_MINIMUM=3.12 -DCRC32C_BUILD_BENCHMARKS=no -DCRC32C_BUILD_TESTS=no -DBUILD_SHARED_LIBS=yes -DCMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=yes -DCRC32C_USE_GLOG=0 -DCMAKE_INSTALL_PREFIX:PATH=C:\tmpfs\src\github\python-crc32c\build\RelWithDebInfo ..
+    py -!python_version_trimmed!-64 -m cmake -G "Visual Studio 17 2022" -A x64 -DCMAKE_POLICY_VERSION_MINIMUM=3.12 -DCRC32C_BUILD_BENCHMARKS=no -DCRC32C_BUILD_TESTS=no -DBUILD_SHARED_LIBS=yes -DCMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=yes -DCRC32C_USE_GLOG=0 -DCMAKE_INSTALL_PREFIX:PATH="%CRC32C_INSTALL_PREFIX%" ..
 
     py -!python_version_trimmed!-64 -m cmake --build . --config "%CONFIGURATION%" --target install