diff --git a/tools/lint/BUILD b/tools/lint/BUILD
index 57d4e08..55cccff 100644
--- a/tools/lint/BUILD
+++ b/tools/lint/BUILD
@@ -35,6 +35,17 @@
 )
 
 sh_binary(
+    name = "yapf",
+    srcs = ["yapf.sh"],
+    data = [
+        "@python_yapf",
+    ],
+    deps = [
+        "@bazel_tools//tools/bash/runfiles",
+    ],
+)
+
+sh_binary(
     name = "prettier",
     srcs = ["prettier.sh"],
     data = [
@@ -56,6 +67,7 @@
         ":gofmt",
         ":prettier",
         ":rustfmt",
+        ":yapf",
         "//:gazelle-runner",
         "//tools/go:mirror_go_repos",
         "//tools/go:tweak_gazelle_go_deps",
diff --git a/tools/lint/run-ci.sh b/tools/lint/run-ci.sh
index a036c06..5e48da6 100755
--- a/tools/lint/run-ci.sh
+++ b/tools/lint/run-ci.sh
@@ -89,6 +89,10 @@
     ./tools/lint/prettier
 }
 
+yapf() {
+    ./tools/lint/yapf
+}
+
 git_status_is_clean() {
     cd "${BUILD_WORKSPACE_DIRECTORY}"
     if ! git diff --quiet; then
@@ -110,6 +114,7 @@
     tweak_cargo_raze
     buildifier
     prettier
+    yapf
     git_status_is_clean  # This must the last linter.
 )
 
diff --git a/tools/lint/yapf.sh b/tools/lint/yapf.sh
new file mode 100755
index 0000000..404d5fd
--- /dev/null
+++ b/tools/lint/yapf.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# --- begin runfiles.bash initialization v2 ---
+# Copy-pasted from the Bazel Bash runfiles library v2.
+set -uo pipefail; f=bazel_tools/tools/bash/runfiles/runfiles.bash
+source "${RUNFILES_DIR:-/dev/null}/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "${RUNFILES_MANIFEST_FILE:-/dev/null}" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$0.runfiles/$f" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  source "$(grep -sm1 "^$f " "$0.exe.runfiles_manifest" | cut -f2- -d' ')" 2>/dev/null || \
+  { echo>&2 "ERROR: cannot find $f"; exit 1; }; f=; set -e
+# --- end runfiles.bash initialization v2 ---
+
+readonly YAPF="$(rlocation python_yapf/python_yapf)"
+
+# Run everything from the root of the tree.
+cd "${BUILD_WORKSPACE_DIRECTORY}"
+
+# Find all the Python files in the repo.
+python_files=($(git ls-tree --name-only --full-tree -r @ \
+    | grep -v '^third_party/' \
+    | (grep '\.py$' || :)))
+
+# If we have any Python files, format them.
+if ((${#python_files[@]} > 0)); then
+    exec "${YAPF}" --in-place --parallel --verbose "${python_files[@]}"
+fi