Index: build/modules/BUILD.gn
--- build/modules/BUILD.gn.orig
+++ build/modules/BUILD.gn
@@ -178,7 +178,7 @@ if (use_unified_system_module) {
               ] + cpu_abi_cflags +
               current_win_toolchain_data.include_flags_I_list +
               current_win_toolchain_data.include_flags_imsvc_list
-    } else {
+    } else if (!is_bsd) {
       # We need to pass the sysroot in so that it can scan it to generate a
       # modulemap for the sysroot headers.
       args += [
