Index: lib/CMakeLists.txt
===================================================================
--- lib/CMakeLists.txt
+++ lib/CMakeLists.txt
@@ -72,9 +72,14 @@
 add_library_flags_if(LIBCXX_HAS_C_LIB c)
 add_library_flags_if(LIBCXX_HAS_M_LIB m)
 add_library_flags_if(LIBCXX_HAS_RT_LIB rt)
-add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s)
 add_library_flags_if(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB atomic)
 
+if (LIBCXXABI_USE_LLVM_UNWINDER)
+  add_library_flags(unwind)
+else()
+  add_library_flags_if(LIBCXX_HAS_GCC_S_LIB gcc_s)
+endif()
+
 # Setup flags.
 if (NOT WIN32)
   add_flags_if_supported(-fPIC)