Index: Makefile.inc1
===================================================================
--- Makefile.inc1
+++ Makefile.inc1
@@ -175,11 +175,11 @@
 .endif
 .endif
 .if ${MACHINE} == ${TARGET} && ${MACHINE_ARCH} == ${TARGET_ARCH} && !defined(CROSS_BUILD_TESTING)
-OBJTREE=	${MAKEOBJDIRPREFIX}
+OBJTREE=	${MAKEOBJDIRPREFIX}${.CURDIR}
 .else
-OBJTREE=	${MAKEOBJDIRPREFIX}/${TARGET}.${TARGET_ARCH}
+OBJTREE=	${MAKEOBJDIRPREFIX}${.CURDIR}/${TARGET}.${TARGET_ARCH}
 .endif
-WORLDTMP=	${OBJTREE}${.CURDIR}/tmp
+WORLDTMP=	${OBJTREE}/tmp
 # /usr/games added for fortune which depend on strfile
 BPATH=		${WORLDTMP}/legacy/usr/sbin:${WORLDTMP}/legacy/usr/bin:${WORLDTMP}/legacy/usr/games:${WORLDTMP}/legacy/bin
 XPATH=		${WORLDTMP}/usr/sbin:${WORLDTMP}/usr/bin:${WORLDTMP}/usr/games
@@ -352,8 +352,8 @@
 
 .if ${TARGET_ARCH} == "amd64" || ${TARGET_ARCH} == "powerpc64"
 # 32 bit world
-LIB32_OBJTREE=	${OBJTREE}${.CURDIR}/world32
-LIB32TMP=	${OBJTREE}${.CURDIR}/lib32
+LIB32_OBJTREE=	${OBJTREE}/world32
+LIB32TMP=	${OBJTREE}/lib32
 
 .if ${TARGET_ARCH} == "amd64"
 .if empty(TARGET_CPUTYPE)
@@ -473,9 +473,9 @@
 .else
 	rm -rf ${WORLDTMP}/legacy/usr/include
 #	XXX - These three can depend on any header file.
-	rm -f ${OBJTREE}${.CURDIR}/usr.bin/kdump/ioctl.c
-	rm -f ${OBJTREE}${.CURDIR}/usr.bin/kdump/kdump_subr.c
-	rm -f ${OBJTREE}${.CURDIR}/usr.bin/truss/ioctl.c
+	rm -f ${OBJTREE}/usr.bin/kdump/ioctl.c
+	rm -f ${OBJTREE}/usr.bin/kdump/kdump_subr.c
+	rm -f ${OBJTREE}/usr.bin/truss/ioctl.c
 .endif
 .for _dir in \
     lib usr legacy/bin legacy/usr
@@ -1176,6 +1176,7 @@
 	@echo "ERROR: Source upgrades from versions prior to 8.0 not supported."; \
 	false
 .endif
+# Note that MAKEOBJDIRPREFIX here is actually the parent make's WORLDTMP.
 .for _tool in tools/build
 	${_+_}@${ECHODIR} "===> ${_tool} (obj,includes,depend,all,install)"; \
 	    cd ${.CURDIR}/${_tool} && \
@@ -1282,6 +1283,8 @@
 #	Please document (add comment) why something is in 'bootstrap-tools'.
 #	Try to bound the building of the bootstrap-tool to just the
 #	FreeBSD versions that need the tool built at this stage of the build.
+#
+# NB: For this target, MAKEOBJDIRPREFIX is the parent's ${WORLDTMP}.
 bootstrap-tools: .MAKE
 .for _tool in \
     ${_clang_tblgen} \
@@ -1362,9 +1365,9 @@
 # kernel-tools: Build kernel-building tools
 #
 kernel-tools: .MAKE
-	mkdir -p ${MAKEOBJDIRPREFIX}/usr
+	mkdir -p ${OBJTREE}/usr
 	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.usr.dist \
-	    -p ${MAKEOBJDIRPREFIX}/usr >/dev/null
+	    -p ${OBJTREE}/usr >/dev/null
 
 #
 # cross-tools: Build cross-building tools
@@ -1917,7 +1920,7 @@
 .error XDTP variable should be an absolute path
 .endif
 
-CDBENV=MAKEOBJDIRPREFIX=${MAKEOBJDIRPREFIX}/${XDDIR} \
+CDBENV=MAKEOBJDIRPREFIX=${OBJTREE}/${XDDIR} \
 	INSTALL="sh ${.CURDIR}/tools/install.sh"
 CDENV= ${CDBENV} \
 	_SHLIBDIRPREFIX=${XDDESTDIR} \
@@ -1929,7 +1932,7 @@
 	CPP="${CPP} ${CD2CFLAGS}" \
 	MACHINE=${TARGET} MACHINE_ARCH=${TARGET_ARCH}
 
-CDTMP=	${MAKEOBJDIRPREFIX}/${XDDIR}/${.CURDIR}/tmp
+CDTMP=	${OBJTREE}/${XDDIR}/${.CURDIR}/tmp
 CDMAKE=${CDENV} PATH=${CDTMP}/usr/bin:${PATH} ${MAKE} ${NOFUN}
 CD2MAKE=${CD2ENV} PATH=${CDTMP}/usr/bin:${XDDESTDIR}/usr/bin:${PATH} ${MAKE} ${NOFUN}
 XDDESTDIR=${DESTDIR}/${XDTP}