Index: llvm-toolchain-snapshot_12~++20210126092700+956d8e02e8a5/libcxx/include/atomic
===================================================================
--- llvm-toolchain-snapshot_12~++20210126092700+956d8e02e8a5.orig/libcxx/include/atomic
+++ llvm-toolchain-snapshot_12~++20210126092700+956d8e02e8a5/libcxx/include/atomic
@@ -2791,10 +2791,15 @@ typedef conditional<_LIBCPP_CONTENTION_L
 typedef conditional<_LIBCPP_CONTENTION_LOCK_FREE, __cxx_contention_t, unsigned char>::type      __libcpp_unsigned_lock_free;
 #else
     // No signed/unsigned lock-free types
+#define NO_LOCK_FREE
 #endif
 
+#ifndef NO_LOCK_FREE
 typedef atomic<__libcpp_signed_lock_free> atomic_signed_lock_free;
 typedef atomic<__libcpp_unsigned_lock_free> atomic_unsigned_lock_free;
+#endif
+
+#undef NO_LOCK_FREE
 
 #define ATOMIC_FLAG_INIT {false}
 #define ATOMIC_VAR_INIT(__v) {__v}