How to disable c++11 feature cxx_unicode_literals in Xcode 7.2

I need to compile a C++ project in Xcode 7.2 using C++11 dialect (-std=c++11 option), but using libstdc++ (GNU C++ standard library) which doesn't have all C++11 definitions/declarations.

Some third party library include header checks for c++11 feature cxx_unicode_literals which is not available using: __has_feature(cxx_unicode_literals)

Is there a way to pass a compiler option which will disable cxx_unicode_literals feature so I don't need to recompile third party library?