diff --git a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
index 10b4e4e0ea46..8e10babb332a 100644
--- a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -153,6 +153,7 @@ if (current_toolchain == default_toolchain) {
       "__algorithm/upper_bound.h",
       "__availability",
       "__bit/bit_cast.h",
+      "__bit/byteswap.h",
       "__bit_reference",
       "__bits",
       "__bsd_locale_defaults.h",