Index: clangd/CMakeLists.txt
===================================================================
--- clangd/CMakeLists.txt
+++ clangd/CMakeLists.txt
@@ -2,6 +2,11 @@
   Support
   )
 
+set(CLANGD_ATOMIC_LIB "")
+if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
+  list(APPEND CLANGD_ATOMIC_LIB atomic)
+endif()
+
 add_clang_library(clangDaemon
   ClangdLSPServer.cpp
   ClangdServer.cpp
@@ -48,6 +53,7 @@
   clangToolingCore
   clangToolingRefactor
   ${LLVM_PTHREAD_LIB}
+  ${CLANGD_ATOMIC_LIB}
   )
 
 if( LLVM_LIB_FUZZING_ENGINE OR LLVM_USE_SANITIZE_COVERAGE )