diff --git Makefile.inc1 Makefile.inc1
index dd17644c..0daa440 100644
--- Makefile.inc1
+++ Makefile.inc1
@@ -646,6 +646,8 @@ _worldtmp: .PHONY
 	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.groff.dist \
 	    -p ${WORLDTMP}/legacy/usr >/dev/null
 .endif
+	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.include.dist \
+	    -p ${WORLDTMP}/legacy/usr/include >/dev/null
 	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.usr.dist \
 	    -p ${WORLDTMP}/usr >/dev/null
 	mtree -deU -f ${.CURDIR}/etc/mtree/BSD.include.dist \
diff --git tools/build/Makefile tools/build/Makefile
index 2617d8d..3d756a3 100644
--- tools/build/Makefile
+++ tools/build/Makefile
@@ -4,9 +4,11 @@
 
 LIB=		egacy
 SRC=
-INCSGROUPS=	INCS
+INCSGROUPS=	INCS SYSINCS
 INCS=
 
+SYSINCSDIR=	${INCLUDEDIR}/sys
+
 BOOTSTRAPPING?=	0
 
 _WITH_PWCACHEDB!= grep -c pwcache_groupdb /usr/include/grp.h || true
@@ -33,6 +35,9 @@ SRCS+=		reallocarray.c
 CFLAGS+=	-I${.CURDIR}/../../lib/libc/include
 .endif
 
+.PATH:		${SRCTOP}/sys/sys
+SYSINCS+=	elf_common.h
+
 .if empty(SRCS)
 SRCS=		dummy.c
 .endif