Index: llvm/trunk/unittests/ExecutionEngine/Orc/CMakeLists.txt
===================================================================
--- llvm/trunk/unittests/ExecutionEngine/Orc/CMakeLists.txt
+++ llvm/trunk/unittests/ExecutionEngine/Orc/CMakeLists.txt
@@ -24,4 +24,9 @@
   SymbolStringPoolTest.cpp
   )
 
-target_link_libraries(OrcJITTests PRIVATE ${LLVM_PTHREAD_LIB})
+set(ORC_JIT_TEST_LIBS ${LLVM_PTHREAD_LIB})
+if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
+  list(APPEND ORC_JIT_TEST_LIBS atomic)
+endif()
+
+target_link_libraries(OrcJITTests PRIVATE ${ORC_JIT_TEST_LIBS})