Problem with intrinsics

Hi,
I faced the following problem when trying to use klee over the llvm format file formed after using wllvm. Does there exist any solution to this?

LLVM ERROR: Code generator does not support intrinsic function ‘llvm.objectsize.i32’!

If you want to avoid generating calls to llvm.objectsize from C code, you
might want to try passing -D_FORTIFY_SOURCE=0 to clang.

-Eli