However, the offending compiler command doesn't seem to have anything to do with the linker. Any ideas?
This looks like it could be a shell or Makefile problem. You should probably visit http://www.open-mpi.org/community/help/ and post all the requested info to the Open MPI user's mailing list. It is likely not an intel compiler-specific problem (I build with the Intel 11.1 compiler all the time).