diff --git a/packages/google-cloud-binary-authorization/.kokoro/build.sh b/packages/google-cloud-binary-authorization/.kokoro/build.sh
index cd5499245172..aa7486cbea75 100755
--- a/packages/google-cloud-binary-authorization/.kokoro/build.sh
+++ b/packages/google-cloud-binary-authorization/.kokoro/build.sh
@@ -41,7 +41,7 @@ python3 -m pip install --upgrade --quiet nox
 python3 -m nox --version
 
 # If this is a continuous build, send the test log to the FlakyBot.
-# See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+# See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"continuous"* ]]; then
   cleanup() {
     chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
diff --git a/packages/google-cloud-binary-authorization/.kokoro/test-samples-impl.sh b/packages/google-cloud-binary-authorization/.kokoro/test-samples-impl.sh
index 311a8d54b9f1..8a324c9c7bc6 100755
--- a/packages/google-cloud-binary-authorization/.kokoro/test-samples-impl.sh
+++ b/packages/google-cloud-binary-authorization/.kokoro/test-samples-impl.sh
@@ -80,7 +80,7 @@ for file in samples/**/requirements.txt; do
     EXIT=$?
 
     # If this is a periodic build, send the test log to the FlakyBot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
     if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
       chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
       $KOKORO_GFILE_DIR/linux_amd64/flakybot
diff --git a/packages/google-cloud-binary-authorization/CONTRIBUTING.rst b/packages/google-cloud-binary-authorization/CONTRIBUTING.rst
index bb5072f68b59..3ba80fd0a1d7 100644
--- a/packages/google-cloud-binary-authorization/CONTRIBUTING.rst
+++ b/packages/google-cloud-binary-authorization/CONTRIBUTING.rst
@@ -50,9 +50,9 @@ You'll have to create a development environment using a Git checkout:
    # Configure remotes such that you can pull changes from the googleapis/python-binary-authorization
    # repository into your local repository.
    $ git remote add upstream git@github.com:googleapis/python-binary-authorization.git
-   # fetch and merge changes from upstream into master
+   # fetch and merge changes from upstream into main
    $ git fetch upstream
-   $ git merge upstream/master
+   $ git merge upstream/main
 
 Now your local repo is set up such that you will push changes to your GitHub
 repo, from which you can submit a pull request.
@@ -110,12 +110,12 @@ Coding Style
   variables::
 
    export GOOGLE_CLOUD_TESTING_REMOTE="upstream"
-   export GOOGLE_CLOUD_TESTING_BRANCH="master"
+   export GOOGLE_CLOUD_TESTING_BRANCH="main"
 
   By doing this, you are specifying the location of the most up-to-date
   version of ``python-binary-authorization``. The the suggested remote name ``upstream``
   should point to the official ``googleapis`` checkout and the
-  the branch should be the main branch on that remote (``master``).
+  the branch should be the main branch on that remote (``main``).
 
 - This repository contains configuration for the
   `pre-commit <https://pre-commit.com/>`__ tool, which automates checking
@@ -209,7 +209,7 @@ The `description on PyPI`_ for the project comes directly from the
 ``README``. Due to the reStructuredText (``rst``) parser used by
 PyPI, relative links which will work on GitHub (e.g. ``CONTRIBUTING.rst``
 instead of
-``https://github.com/googleapis/python-binary-authorization/blob/master/CONTRIBUTING.rst``)
+``https://github.com/googleapis/python-binary-authorization/blob/main/CONTRIBUTING.rst``)
 may cause problems creating links or rendering the description.
 
 .. _description on PyPI: https://pypi.org/project/google-cloud-binary-authorization
@@ -234,7 +234,7 @@ We support:
 
 Supported versions can be found in our ``noxfile.py`` `config`_.
 
-.. _config: https://github.com/googleapis/python-binary-authorization/blob/master/noxfile.py
+.. _config: https://github.com/googleapis/python-binary-authorization/blob/main/noxfile.py
 
 
 We also explicitly decided to support Python 3 beginning with version 3.6.
diff --git a/packages/google-cloud-binary-authorization/docs/conf.py b/packages/google-cloud-binary-authorization/docs/conf.py
index f9f210a94aff..3e51f11a82fb 100644
--- a/packages/google-cloud-binary-authorization/docs/conf.py
+++ b/packages/google-cloud-binary-authorization/docs/conf.py
@@ -76,8 +76,8 @@
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'
 
-# The master toctree document.
-master_doc = "index"
+# The root toctree document.
+root_doc = "index"
 
 # General information about the project.
 project = "google-cloud-binary-authorization"
@@ -280,7 +280,7 @@
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-binary-authorization.tex",
         "google-cloud-binary-authorization Documentation",
         author,
@@ -315,7 +315,7 @@
 # (source start file, name, description, authors, manual section).
 man_pages = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-binary-authorization",
         "google-cloud-binary-authorization Documentation",
         [author],
@@ -334,7 +334,7 @@
 #  dir menu entry, description, category)
 texinfo_documents = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-binary-authorization",
         "google-cloud-binary-authorization Documentation",
         author,
diff --git a/packages/google-cloud-binary-authorization/owlbot.py b/packages/google-cloud-binary-authorization/owlbot.py
index 41cc9451fa60..659cd168fbe4 100644
--- a/packages/google-cloud-binary-authorization/owlbot.py
+++ b/packages/google-cloud-binary-authorization/owlbot.py
@@ -43,7 +43,61 @@
 python.py_samples(skip_readmes=True)
 s.move(
     templated_files,
-    excludes=[".coveragerc"],  # the microgenerator has a goodcoveragerc file
+    excludes=[".coveragerc"],  # the microgenerator has a good coveragerc file
+)
+
+# Remove the replacements below once https://github.com/googleapis/synthtool/pull/1188 is merged
+
+# Update googleapis/repo-automation-bots repo to main in .kokoro/*.sh files
+s.replace(".kokoro/*.sh", "repo-automation-bots/tree/master", "repo-automation-bots/tree/main")
+
+# Customize CONTRIBUTING.rst to replace master with main
+s.replace(
+    "CONTRIBUTING.rst",
+    "fetch and merge changes from upstream into master",
+    "fetch and merge changes from upstream into main",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "git merge upstream/master",
+    "git merge upstream/main",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    """export GOOGLE_CLOUD_TESTING_BRANCH=\"master\"""",
+    """export GOOGLE_CLOUD_TESTING_BRANCH=\"main\"""",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "remote \(``master``\)",
+    "remote (``main``)",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "blob/master/CONTRIBUTING.rst",
+    "blob/main/CONTRIBUTING.rst",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "blob/master/noxfile.py",
+    "blob/main/noxfile.py",
+)
+
+s.replace(
+    "docs/conf.py",
+    "master_doc",
+    "root_doc",
+)
+
+s.replace(
+    "docs/conf.py",
+    "# The master toctree document.",
+    "# The root toctree document.",
 )
 
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)