diff --git a/synthtool/gcp/templates/python_library/.kokoro/build.sh b/synthtool/gcp/templates/python_library/.kokoro/build.sh
index 758f299e6..400197473 100755
--- a/synthtool/gcp/templates/python_library/.kokoro/build.sh
+++ b/synthtool/gcp/templates/python_library/.kokoro/build.sh
@@ -15,7 +15,11 @@
 
 set -eo pipefail
 
-cd github/{{ metadata['repo']['repo'].split('/')[1] }}
+if [[ -z "${PROJECT_ROOT:-}" ]]; then
+    PROJECT_ROOT="github/{{ metadata['repo']['repo'].split('/')[1] }}"
+fi
+
+cd "${PROJECT_ROOT}"
 
 # Disable buffering, so that the logs stream through.
 export PYTHONUNBUFFERED=1
@@ -30,16 +34,16 @@ export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
 export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
 
 # Remove old nox
-python3.6 -m pip uninstall --yes --quiet nox-automation
+python3 -m pip uninstall --yes --quiet nox-automation
 
 # Install nox
-python3.6 -m pip install --upgrade --quiet nox
-python3.6 -m nox --version
+python3 -m pip install --upgrade --quiet nox
+python3 -m nox --version
 
 # If NOX_SESSION is set, it only runs the specified session,
 # otherwise run all the sessions.
 if [[ -n "${NOX_SESSION:-}" ]]; then
-    python3.6 -m nox -s "${NOX_SESSION:-}"
+    python3 -m nox -s ${NOX_SESSION:-}
 else
-    python3.6 -m nox
+    python3 -m nox
 fi
diff --git a/synthtool/gcp/templates/python_library/.kokoro/docs/docs-presubmit.cfg b/synthtool/gcp/templates/python_library/.kokoro/docs/docs-presubmit.cfg
index 111810782..91f8a3be0 100644
--- a/synthtool/gcp/templates/python_library/.kokoro/docs/docs-presubmit.cfg
+++ b/synthtool/gcp/templates/python_library/.kokoro/docs/docs-presubmit.cfg
@@ -15,3 +15,14 @@ env_vars: {
     key: "TRAMPOLINE_IMAGE_UPLOAD"
     value: "false"
 }
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: github/{{ metadata['repo']['repo'].split('/')[1] }}/.kokoro/build.sh"
+}
+
+# Only run this nox session.
+env_vars: {
+    key: "NOX_SESSION"
+    value: "docs docfx"
+}
diff --git a/synthtool/gcp/templates/python_library/.trampolinerc b/synthtool/gcp/templates/python_library/.trampolinerc
index 995ee2911..c7d663ae9 100644
--- a/synthtool/gcp/templates/python_library/.trampolinerc
+++ b/synthtool/gcp/templates/python_library/.trampolinerc
@@ -18,12 +18,14 @@
 required_envvars+=(
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
+    "NOX_SESSION"
 )
 
 # Add env vars which are passed down into the container here.
 pass_down_envvars+=(
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
+    "NOX_SESSION"
 )
 
 # Prevent unintentional override on the default image.
diff --git a/synthtool/gcp/templates/python_library/noxfile.py.j2 b/synthtool/gcp/templates/python_library/noxfile.py.j2
index afec6442c..ee187e795 100644
--- a/synthtool/gcp/templates/python_library/noxfile.py.j2
+++ b/synthtool/gcp/templates/python_library/noxfile.py.j2
@@ -30,6 +30,17 @@ DEFAULT_PYTHON_VERSION="{{ default_python_version }}"
 SYSTEM_TEST_PYTHON_VERSIONS=[{% for v in system_test_python_versions %}"{{v}}"{% if not loop.last %},{% endif %}{% endfor %}]
 UNIT_TEST_PYTHON_VERSIONS=[{% for v in unit_test_python_versions %}"{{v}}"{% if not loop.last %},{% endif %}{% endfor %}]
 
+# 'docfx' is excluded since it only needs to run in 'docs-presubmit'
+nox.options.sessions = [
+    "unit",
+    "system",
+    "cover",
+    "lint",
+    "lint_setup_py",
+    "blacken",
+    "docs",
+]
+
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
     """Run linters.