diff --git a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
index c0fa80aebc71..d79c88a58f32 100644
--- a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -297,6 +297,7 @@ if (current_toolchain == default_toolchain) {
       "__utility/rel_ops.h",
       "__utility/swap.h",
       "__utility/to_underlying.h",
+      "__variant/monostate.h",
       "algorithm",
       "any",
       "array",