Index: lldb/cmake/modules/LLDBConfig.cmake
===================================================================
--- lldb/cmake/modules/LLDBConfig.cmake
+++ lldb/cmake/modules/LLDBConfig.cmake
@@ -170,9 +170,6 @@
 append_if(CXX_SUPPORTS_NO_STRICT_ALIASING "-Wno-strict-aliasing" CMAKE_CXX_FLAGS)
 
 # Disable Clang warnings
-check_cxx_compiler_flag("-Wno-deprecated-register" CXX_SUPPORTS_NO_DEPRECATED_REGISTER)
-append_if(CXX_SUPPORTS_NO_DEPRECATED_REGISTER "-Wno-deprecated-register" CMAKE_CXX_FLAGS)
-
 check_cxx_compiler_flag("-Wno-vla-extension" CXX_SUPPORTS_NO_VLA_EXTENSION)
 append_if(CXX_SUPPORTS_NO_VLA_EXTENSION "-Wno-vla-extension" CMAKE_CXX_FLAGS)