This is xnu-8019. See this file in:
Directory listing for xnu-8019//libkern/kxld
Makefile
WKdmCompress.c
WKdmDecompress.c
kxld.c
kxld_array.c
kxld_array.h
kxld_copyright.c
kxld_demangle.c
kxld_demangle.h
kxld_dict.c
kxld_dict.h
kxld_kext.c
kxld_kext.h
kxld_object.c
kxld_object.h
kxld_reloc.c
kxld_reloc.h
kxld_sect.c
kxld_sect.h
kxld_seg.c
kxld_seg.h
kxld_splitinfolc.c
kxld_splitinfolc.h
kxld_srcversion.c
kxld_srcversion.h
kxld_sym.c
kxld_sym.h
kxld_symtab.c
kxld_symtab.h
kxld_util.c
kxld_util.h
kxld_uuid.c
kxld_uuid.h
kxld_versionmin.c
kxld_versionmin.h
kxld_vtable.c
kxld_vtable.h
tests/