Building DMD

[Inquie via Digitalmars-d-learn]

I am trying to build DMD 64-bit. I was able to build everything 
after getting the paths fixed for zlib, druntime, and phobos. 
Everything seems to compile. I replaced all the files generated 
in to the dmd directories of the old ones. (phobos64.lib, 
gcstub.obj, dmd.exe)

But anytime I build my projects that worked fine in the x86 
compiler I get the errors:

  Error 42: Symbol Undefined __d_arrayboundsp
  Error 42: Symbol Undefined __d_assertp

These seem like dmd runtime functions or something similar but 
not sure why they don't exist.

Any ideas? Are these functions suppose to be in phobos or 
druntime? and why aren't they showing up when I build from 
sources and replaced everything, I believe, correctly?