amd64 head -r351153 self-built but via devel/llvm90: 'objcopy: elf_update() failed: Layout constraint violation' for gptboot.bin

I upgraded to head -r351153 and then attempted a buildworld
buildkernel via devel/llvm90 (rc2 via ports head -r509054),
but that (from scratch) build attempt got:

--- gptboot.bin ---
objcopy: elf_update() failed: Layout constraint violation
*** [gptboot.bin] Error code 1
make[5]: *** gptboot.bin removed

make[5]: stopped in /usr/src/stand/i386/gptboot
.ERROR_TARGET='gptboot.bin'
.ERROR_META_FILE='/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/stand/i386/gptboot/gptboot.bin.meta'
.MAKE.LEVEL='5'
MAKEFILE=''
.MAKE.MODE='meta missing-filemon=yes missing-meta=yes silent=yes verbose'
_ERROR_CMD='objcopy -S -O binary gptboot.out gptboot.bin;'
.CURDIR='/usr/src/stand/i386/gptboot'
.MAKE='make'
.OBJDIR='/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/stand/i386/gptboot'
.TARGETS='all'
DESTDIR='/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp'
LD_LIBRARY_PATH=''
MACHINE='amd64'
MACHINE_ARCH='amd64'
MAKEOBJDIRPREFIX=''
MAKESYSPATH='/usr/src/share/mk'
MAKE_VERSION='20181221'
PATH='/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp/usr/sbin:/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp/usr/bin:/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp/legacy/usr/sbin:/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp/legacy/usr/bin:/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64/tmp/legacy/bin::/sbin:/bin:/usr/sbin:/usr/bin'
SRCTOP='/usr/src'
OBJTOP='/usr/obj/amd64_xtoolchain-llvm/amd64.amd64/usr/src/amd64.amd64'
.MAKE.MAKEFILES='/usr/src/share/mk/sys.mk /usr/src/share/mk/local.sys.env.mk /usr/src/share/mk/src.sys.env.mk /root/src.configs/src.conf.amd64-xtoolchain-llvm.amd64-host /usr/src/share/mk/bsd.mkopt.mk /usr/src/share/mk/src.sys.obj.mk /usr/src/share/mk/auto.obj.mk /usr/src/share/mk/bsd.suffixes.mk /root/src.configs/make.conf /usr/src/share/mk/local.sys.mk /usr/src/share/mk/src.sys.mk /dev/null /usr/src/stand/i386/gptboot/Makefile /usr/src/share/mk/bsd.init.mk /usr/src/share/mk/bsd.opts.mk /usr/src/share/mk/bsd.cpu.mk /usr/src/share/mk/local.init.mk /usr/src/share/mk/src.init.mk /usr/src/stand/i386/gptboot/../Makefile.inc /usr/src/share/mk/bsd.linker.mk /usr/src/stand/i386/gptboot/../../Makefile.inc /usr/src/stand/i386/gptboot/../../defs.mk /usr/src/share/mk/src.opts.mk /usr/src/share/mk/bsd.own.mk /usr/src/share/mk/bsd.compiler.mk /usr/src/share/mk/bsd.compiler.mk /usr/src/share/mk/bsd.prog.mk /usr/src/share/mk/bsd.libnames.mk /usr/src/share/mk/src.libnames.mk /usr/src/share/mk/bsd.nls.mk /usr/src/share/mk/bsd.confs.mk /usr/src/share/mk/bsd.files.mk /usr/src/share/mk/bsd.dirs.mk /usr/src/share/mk/bsd.incs.mk /usr/src/share/mk/bsd.links.mk /usr/src/share/mk/bsd.man.mk /usr/src/share/mk/bsd.dep.mk /usr/src/share/mk/bsd.clang-analyze.mk /usr/src/share/mk/bsd.obj.mk /usr/src/share/mk/bsd.subdir.mk /usr/src/share/mk/bsd.sys.mk'
.PATH='. /usr/src/stand/i386/gptboot /usr/src/stand/i386/boot2 /usr/src/stand/i386/common /usr/src/stand/libsa'
1 error

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)