Index: cmake/LLDBDependencies.cmake
===================================================================
--- cmake/LLDBDependencies.cmake
+++ cmake/LLDBDependencies.cmake
@@ -157,6 +157,11 @@
     endif()
   endif()
 endif()
+
+if (NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB )
+    list(APPEND LLDB_SYSTEM_LIBS atomic)
+endif()
+
 # On FreeBSD/NetBSD backtrace() is provided by libexecinfo, not libc.
 if (CMAKE_SYSTEM_NAME MATCHES "FreeBSD" OR CMAKE_SYSTEM_NAME MATCHES "NetBSD")
   list(APPEND LLDB_SYSTEM_LIBS execinfo)