diff --git a/.kokoro/lint/presubmit.cfg b/.kokoro/lint/presubmit.cfg
index 1cf6a4b7382..d74d307bbed 100644
--- a/.kokoro/lint/presubmit.cfg
+++ b/.kokoro/lint/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python2.7/presubmit.cfg b/.kokoro/python2.7/presubmit.cfg
index 1cf6a4b7382..d74d307bbed 100644
--- a/.kokoro/python2.7/presubmit.cfg
+++ b/.kokoro/python2.7/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python3.10/presubmit.cfg b/.kokoro/python3.10/presubmit.cfg
index 23bb83500df..158c832fcd5 100644
--- a/.kokoro/python3.10/presubmit.cfg
+++ b/.kokoro/python3.10/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python3.6/presubmit.cfg b/.kokoro/python3.6/presubmit.cfg
index 1cf6a4b7382..d74d307bbed 100644
--- a/.kokoro/python3.6/presubmit.cfg
+++ b/.kokoro/python3.6/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python3.7/presubmit.cfg b/.kokoro/python3.7/presubmit.cfg
index 2196a2e4085..5fe1a87a9a8 100644
--- a/.kokoro/python3.7/presubmit.cfg
+++ b/.kokoro/python3.7/presubmit.cfg
@@ -16,5 +16,5 @@
 
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python3.8/presubmit.cfg b/.kokoro/python3.8/presubmit.cfg
index 1cf6a4b7382..d74d307bbed 100644
--- a/.kokoro/python3.8/presubmit.cfg
+++ b/.kokoro/python3.8/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/python3.9/presubmit.cfg b/.kokoro/python3.9/presubmit.cfg
index 1cf6a4b7382..d74d307bbed 100644
--- a/.kokoro/python3.9/presubmit.cfg
+++ b/.kokoro/python3.9/presubmit.cfg
@@ -17,5 +17,5 @@
 # Tell the trampoline which build file to use.
 env_vars: {
     key: "TRAMPOLINE_BUILD_FILE"
-    value: ".kokoro/tests/run_tests_diff_master.sh"
+    value: ".kokoro/tests/run_tests_diff_main.sh"
 }
diff --git a/.kokoro/tests/run_tests.sh b/.kokoro/tests/run_tests.sh
index 78807e23fc4..100fbe53dfe 100755
--- a/.kokoro/tests/run_tests.sh
+++ b/.kokoro/tests/run_tests.sh
@@ -21,16 +21,16 @@ shopt -s globstar
 
 DIFF_FROM=""
 
-# `--only-diff-master` will only run tests on project changes on the
-# last common commit from the master branch.
-if [[ $* == *--only-diff-master* ]]; then
+# `--only-diff-main` will only run tests on project changes on the
+# last common commit from the main branch.
+if [[ $* == *--only-diff-main* ]]; then
     set +e
-    git diff --quiet "origin/master..." .kokoro/tests .kokoro/docker \
+    git diff --quiet "origin/main..." .kokoro/tests .kokoro/docker \
 	.kokoro/trampoline_v2.sh
     CHANGED=$?
     set -e
     if [[ "${CHANGED}" -eq 0 ]]; then
-	DIFF_FROM="origin/master..."
+	DIFF_FROM="origin/main..."
     else
 	echo "Changes to test driver files detected. Running full tests."
     fi
diff --git a/.kokoro/tests/run_tests_diff_master.sh b/.kokoro/tests/run_tests_diff_main.sh
similarity index 93%
rename from .kokoro/tests/run_tests_diff_master.sh
rename to .kokoro/tests/run_tests_diff_main.sh
index defbb578bae..de122cfa4fd 100755
--- a/.kokoro/tests/run_tests_diff_master.sh
+++ b/.kokoro/tests/run_tests_diff_main.sh
@@ -13,4 +13,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 mydir="${0%/*}"
-"$mydir"/run_tests.sh --only-diff-master
\ No newline at end of file
+"$mydir"/run_tests.sh --only-diff-main
diff --git a/.kokoro/tests/run_tests_orig.sh b/.kokoro/tests/run_tests_orig.sh
index a00bfacdb08..b641d00495f 100755
--- a/.kokoro/tests/run_tests_orig.sh
+++ b/.kokoro/tests/run_tests_orig.sh
@@ -21,16 +21,16 @@ shopt -s globstar
 
 DIFF_FROM=""
 
-# `--only-diff-master` will only run tests on project changes on the
-# last common commit from the master branch.
-if [[ $* == *--only-diff-master* ]]; then
+# `--only-diff-main` will only run tests on project changes on the
+# last common commit from the main branch.
+if [[ $* == *--only-diff-main* ]]; then
     set +e
-    git diff --quiet "origin/master..." .kokoro/tests .kokoro/docker \
+    git diff --quiet "origin/main..." .kokoro/tests .kokoro/docker \
 	.kokoro/trampoline_v2.sh
     CHANGED=$?
     set -e
     if [[ "${CHANGED}" -eq 0 ]]; then
-	DIFF_FROM="origin/master..."
+	DIFF_FROM="origin/main..."
     else
 	echo "Changes to test driver files detected. Running full tests."
     fi