reg : error while building llvm IR code generator


I get the following error after I have downloaded entire llvm libraries and then compiled the llvm IR code generator code.

fatal error: ‘llvm/IR/DerivedTypes.h’ file not found #include “llvm/IR/DerivedTypes.h” ^ 1 error generated.

Could you please tell me as to why is the above error generated ? And how should I proceed further ?

Thanks and Regards