Building a standalone druntime for LDC

[A. Nicholi]

Hello,

I am trying to build LDC’s druntime by itself (without phobos), 
but it seems that druntime expects to be built alongside DMD, 
which is strange considering I’m building LDC’s version of the 
druntime. Make says: “No rule to make target 
'../dmd/src/osmodel.mak'”

Is it possible to build druntime by itself for LDC? Must I build 
LDC alongside it for every host platform, or may I just specify 
‘-defaultlib=’ with a distro-provided LDC? How should I go about 
doing this?