diff --git a/utils/bazel/llvm-project-overlay/llvm/config.bzl b/utils/bazel/llvm-project-overlay/llvm/config.bzl
--- a/utils/bazel/llvm-project-overlay/llvm/config.bzl
+++ b/utils/bazel/llvm-project-overlay/llvm/config.bzl
@@ -69,6 +69,7 @@
 os_defines = select({
     "@bazel_tools//src/conditions:windows": win32_defines,
     "@bazel_tools//src/conditions:darwin": macos_defines,
+    "@bazel_tools//src/conditions:freebsd": posix_defines,
     "//conditions:default": linux_defines,
 })