diff --git a/blargh.yml b/blargh.yml
new file mode 100644
index 000000000..e5f1aa652
--- /dev/null
+++ b/blargh.yml
@@ -0,0 +1,7 @@
+bumpMinorPreMajor: true
+handleGHRelease: true
+releaseType: java-yoshi
+branches:
+  - handleGHRelease: true
+    releaseType: python
+    branch: java7
\ No newline at end of file
diff --git a/synthtool/languages/python.py b/synthtool/languages/python.py
index 4e99e88e9..78a6a0ff2 100644
--- a/synthtool/languages/python.py
+++ b/synthtool/languages/python.py
@@ -148,6 +148,62 @@ def py_samples(*, root: PathOrStr = None, skip_readmes: bool = False) -> None:
         s.copy([result], excludes=excludes)
 
 
+def configure_previous_major_version_branches() -> None:
+    """Configure releases from previous major version branches by editing
+     `.github/release-please.yml`.
+
+     The current library version is obtained from `version.py` in `google/**/version.py`,
+     or the `setup.py`.
+
+     Releases are configured for all previous major versions. For example,
+     if the library version is currently 3.5.1, the release-please config
+     will include v2, v1, and v0.
+     """
+    if list(Path(".").glob("google/**/version.py")):
+        version_file = list(Path(".").glob("google/**/version.py"))[0]
+    else:
+        version_file = Path("setup.py")
+
+    # In version.py:    __version__ = "1.5.2"
+    # In setup.py:      version = "1.5.2"
+    VERSION_REGEX = (
+        r"(?:__)?version(?:__)?\s*=\s*[\"'](?P<major_version>\d)\.[\d\.]+[\"']"
+    )
+
+    match = re.search(VERSION_REGEX, Path(version_file).read_text())
+
+    if match is not None:
+        major_version = int(match.group("major_version"))
+    else:
+        raise RuntimeError(
+            "Unable to find library version in {} with regex {}".format(
+                version_file, VERSION_REGEX
+            )
+        )
+
+    with open(".github/release-please.yml") as f:
+        release_please_yml = yaml.load(f, Loader=yaml.SafeLoader)
+
+    if major_version > 0 and "branches" not in release_please_yml:
+        branches = []
+        for version in range(major_version - 1, -1, -1):
+            branches.append(
+                {
+                    "branch": f"v{version}",
+                    "handleGHRelease": True,
+                    "releaseType": "python",
+                }
+            )
+
+        with open(".github/release-please.yml", "a") as f:
+            # comments can't be expressed in PyYAML
+            f.write(
+                """# NOTE: this section is generated by synthtool.languages.python
+# See https://github.com/googleapis/synthtool/blob/master/synthtool/languages/python.py\n"""
+            )
+            f.write(yaml.dump({"branches": branches}))
+
+
 def owlbot_main() -> None:
     """Copies files from staging and template directories into current working dir.
 
@@ -202,6 +258,8 @@ def owlbot_main() -> None:
         for noxfile in Path(".").glob("**/noxfile.py"):
             s.shell.run(["nox", "-s", "blacken"], cwd=noxfile.parent, hide_output=False)
 
+    configure_previous_major_version_branches()
+
 
 if __name__ == "__main__":
     owlbot_main()
diff --git a/tests/fixtures/python_library/setup.py b/tests/fixtures/python_library/setup.py
new file mode 100644
index 000000000..4657b2278
--- /dev/null
+++ b/tests/fixtures/python_library/setup.py
@@ -0,0 +1,108 @@
+# Copyright 2018 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# Copyright 2018 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import io
+import os
+
+import setuptools
+
+
+# Package metadata.
+
+name = "google-cloud-texttospeech"
+description = "Google Cloud Text-to-Speech API client library"
+version = "2.11.0"
+# Should be one of:
+# 'Development Status :: 3 - Alpha'
+# 'Development Status :: 4 - Beta'
+# 'Development Status :: 5 - Production/Stable'
+release_status = "Development Status :: 5 - Production/Stable"
+dependencies = [
+    # NOTE: Maintainers, please do not require google-api-core>=2.x.x
+    # Until this issue is closed
+    # https://github.com/googleapis/google-cloud-python/issues/10566
+    "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
+    "proto-plus >= 1.15.0",
+]
+extras = {}
+
+
+# Setup boilerplate below this line.
+
+package_root = os.path.abspath(os.path.dirname(__file__))
+
+readme_filename = os.path.join(package_root, "README.rst")
+with io.open(readme_filename, encoding="utf-8") as readme_file:
+    readme = readme_file.read()
+
+# Only include packages under the 'google' namespace. Do not include tests,
+# benchmarks, etc.
+packages = [
+    package
+    for package in setuptools.PEP420PackageFinder.find()
+    if package.startswith("google")
+]
+
+# Determine which namespaces are needed.
+namespaces = ["google"]
+if "google.cloud" in packages:
+    namespaces.append("google.cloud")
+
+
+setuptools.setup(
+    name=name,
+    version=version,
+    description=description,
+    long_description=readme,
+    author="Google LLC",
+    author_email="googleapis-packages@google.com",
+    license="Apache 2.0",
+    url="https://github.com/googleapis/python-texttospeech",
+    classifiers=[
+        release_status,
+        "Intended Audience :: Developers",
+        "License :: OSI Approved :: Apache Software License",
+        "Programming Language :: Python",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
+        "Operating System :: OS Independent",
+        "Topic :: Internet",
+    ],
+    platforms="Posix; MacOS X; Windows",
+    packages=packages,
+    namespace_packages=namespaces,
+    install_requires=dependencies,
+    extras_require=extras,
+    python_requires=">=3.6",
+    scripts=["scripts/fixup_keywords.py"],
+    include_package_data=True,
+    zip_safe=False,
+)
diff --git a/tests/fixtures/python_library_w_version_py/.repo-metadata.json b/tests/fixtures/python_library_w_version_py/.repo-metadata.json
new file mode 100644
index 000000000..32efa1d54
--- /dev/null
+++ b/tests/fixtures/python_library_w_version_py/.repo-metadata.json
@@ -0,0 +1,13 @@
+{
+  "name": "texttospeech",
+  "name_pretty": "Google Cloud Text-to-Speech",
+  "product_documentation": "https://cloud.google.com/text-to-speech",
+  "client_documentation": "https://googleapis.dev/python/texttospeech/latest",
+  "issue_tracker": "https://issuetracker.google.com/savedsearches/5235428",
+  "release_level": "ga",
+  "language": "python",
+  "repo": "googleapis/python-texttospeech",
+  "distribution_name": "google-cloud-texttospeech",
+  "api_id": "texttospeech.googleapis.com",
+  "requires_billing": true
+}
diff --git a/tests/fixtures/python_library_w_version_py/google/cloud/texttospeech/version.py b/tests/fixtures/python_library_w_version_py/google/cloud/texttospeech/version.py
new file mode 100644
index 000000000..7f6646a76
--- /dev/null
+++ b/tests/fixtures/python_library_w_version_py/google/cloud/texttospeech/version.py
@@ -0,0 +1 @@
+__version__ = "2.11.0"
diff --git a/tests/fixtures/python_library_w_version_py/setup.py b/tests/fixtures/python_library_w_version_py/setup.py
new file mode 100644
index 000000000..4657b2278
--- /dev/null
+++ b/tests/fixtures/python_library_w_version_py/setup.py
@@ -0,0 +1,108 @@
+# Copyright 2018 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# Copyright 2018 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import io
+import os
+
+import setuptools
+
+
+# Package metadata.
+
+name = "google-cloud-texttospeech"
+description = "Google Cloud Text-to-Speech API client library"
+version = "2.11.0"
+# Should be one of:
+# 'Development Status :: 3 - Alpha'
+# 'Development Status :: 4 - Beta'
+# 'Development Status :: 5 - Production/Stable'
+release_status = "Development Status :: 5 - Production/Stable"
+dependencies = [
+    # NOTE: Maintainers, please do not require google-api-core>=2.x.x
+    # Until this issue is closed
+    # https://github.com/googleapis/google-cloud-python/issues/10566
+    "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
+    "proto-plus >= 1.15.0",
+]
+extras = {}
+
+
+# Setup boilerplate below this line.
+
+package_root = os.path.abspath(os.path.dirname(__file__))
+
+readme_filename = os.path.join(package_root, "README.rst")
+with io.open(readme_filename, encoding="utf-8") as readme_file:
+    readme = readme_file.read()
+
+# Only include packages under the 'google' namespace. Do not include tests,
+# benchmarks, etc.
+packages = [
+    package
+    for package in setuptools.PEP420PackageFinder.find()
+    if package.startswith("google")
+]
+
+# Determine which namespaces are needed.
+namespaces = ["google"]
+if "google.cloud" in packages:
+    namespaces.append("google.cloud")
+
+
+setuptools.setup(
+    name=name,
+    version=version,
+    description=description,
+    long_description=readme,
+    author="Google LLC",
+    author_email="googleapis-packages@google.com",
+    license="Apache 2.0",
+    url="https://github.com/googleapis/python-texttospeech",
+    classifiers=[
+        release_status,
+        "Intended Audience :: Developers",
+        "License :: OSI Approved :: Apache Software License",
+        "Programming Language :: Python",
+        "Programming Language :: Python :: 3",
+        "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
+        "Operating System :: OS Independent",
+        "Topic :: Internet",
+    ],
+    platforms="Posix; MacOS X; Windows",
+    packages=packages,
+    namespace_packages=namespaces,
+    install_requires=dependencies,
+    extras_require=extras,
+    python_requires=">=3.6",
+    scripts=["scripts/fixup_keywords.py"],
+    include_package_data=True,
+    zip_safe=False,
+)
diff --git a/tests/test_python_library.py b/tests/test_python_library.py
index 1fe8ff9c4..a0a3ab160 100644
--- a/tests/test_python_library.py
+++ b/tests/test_python_library.py
@@ -13,12 +13,14 @@
 # limitations under the License.
 
 import os
+import shutil
 from pathlib import Path
 
 import pytest
 
 from synthtool import gcp
 from synthtool.sources import templates
+from synthtool.languages import python
 from . import util
 
 
@@ -126,3 +128,38 @@ def test_split_system_tests():
         with open(templated_files / ".kokoro/presubmit/system-3.8.cfg", "r") as f:
             contents = f.read()
             assert "system-3.8" in contents
+
+
+@pytest.mark.parametrize(
+    "fixtures_dir",
+    [
+        Path(__file__).parent / "fixtures/python_library",  # just setup.py
+        Path(__file__).parent
+        / "fixtures/python_library_w_version_py",  # has google/cloud/texttospeech/version.py
+    ],
+)
+def test_configure_previous_major_version_branches(fixtures_dir):
+    with util.copied_fixtures_dir(fixtures_dir):
+        t = templates.Templates(PYTHON_LIBRARY)
+        result = t.render(".github/release-please.yml")
+        os.makedirs(".github")
+        shutil.copy(result, Path(".github/release-please.yml"))
+
+        python.configure_previous_major_version_branches()
+        release_please_yml = Path(".github/release-please.yml").read_text()
+
+        assert (
+            release_please_yml
+            == """releaseType: python
+handleGHRelease: true
+# NOTE: this section is generated by synthtool.languages.python
+# See https://github.com/googleapis/synthtool/blob/master/synthtool/languages/python.py
+branches:
+- branch: v1
+  handleGHRelease: true
+  releaseType: python
+- branch: v0
+  handleGHRelease: true
+  releaseType: python
+"""
+        )