Index: libcxxabi/src/cxa_guard_impl.h
===================================================================
--- libcxxabi/src/cxa_guard_impl.h
+++ libcxxabi/src/cxa_guard_impl.h
@@ -230,18 +230,24 @@
 struct LibcppMutex;
 struct LibcppCondVar;
 
-#ifndef _LIBCXXABI_HAS_NO_THREADS
 struct LibcppMutex {
   LibcppMutex() = default;
   LibcppMutex(LibcppMutex const&) = delete;
   LibcppMutex& operator=(LibcppMutex const&) = delete;
 
+#ifndef _LIBCXXABI_HAS_NO_THREADS
   bool lock() { return std::__libcpp_mutex_lock(&mutex); }
   bool unlock() { return std::__libcpp_mutex_unlock(&mutex); }
+#else
+  bool lock() { return 0; }
+  bool unlock() { return 0; }
+#endif
 
 private:
   friend struct LibcppCondVar;
+#ifndef _LIBCXXABI_HAS_NO_THREADS
   std::__libcpp_mutex_t mutex = _LIBCPP_MUTEX_INITIALIZER;
+#endif
 };
 
 struct LibcppCondVar {
@@ -249,15 +255,23 @@
   LibcppCondVar(LibcppCondVar const&) = delete;
   LibcppCondVar& operator=(LibcppCondVar const&) = delete;
 
+#ifndef _LIBCXXABI_HAS_NO_THREADS
   bool wait(LibcppMutex& mut) {
     return std::__libcpp_condvar_wait(&cond, &mut.mutex);
   }
   bool broadcast() { return std::__libcpp_condvar_broadcast(&cond); }
+#else
+  bool wait(LibcppMutex& mut) {
+    return 0;
+  }
+  bool broadcast() { return 0; }
+#endif
 
 private:
+#ifndef _LIBCXXABI_HAS_NO_THREADS
   std::__libcpp_condvar_t cond = _LIBCPP_CONDVAR_INITIALIZER;
+#endif
 };
-#endif // !defined(_LIBCXXABI_HAS_NO_THREADS)
 
 
 template <class Mutex, class CondVar, Mutex& global_mutex, CondVar& global_cond,