diff --git a/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl b/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
index f65da9e98226b..672ce8c0723ec 100644
--- a/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
+++ b/utils/bazel/llvm-project-overlay/libc/libc_configure_options.bzl
@@ -44,6 +44,11 @@ LIBC_CONFIGURE_OPTIONS = [
     # "LIBC_COPT_STRTOFLOAT_DISABLE_EISEL_LEMIRE",
     # "LIBC_COPT_STRTOFLOAT_DISABLE_SIMPLE_DECIMAL_CONVERSION",
 
+    # Documentation in libc/src/errno/...
+    # Since we're only using Bazel for overlay build for now, explicitly
+    # enforce using the system-provided errno in both tests and release build.
+    "LIBC_ERRNO_MODE=LIBC_ERRNO_MODE_SYSTEM",
+
     # Documentation in libc/src/__support/libc_assert.h
     # "LIBC_COPT_USE_C_ASSERT",
 ]