Index: Makefile.inc1
===================================================================
--- Makefile.inc1
+++ Makefile.inc1
@@ -686,6 +686,9 @@
 XMAKE=		${BMAKE} \
 		TARGET=${TARGET} TARGET_ARCH=${TARGET_ARCH} \
 		MK_GDB=no MK_TESTS=no
+.if empty(.MAKEOVERRIDES:MMK_LLVM_TARGET_ALL)
+XMAKE+=		MK_LLVM_TARGET_ALL=no
+.endif
 
 # kernel-tools stage
 KTMAKEENV=	INSTALL="sh ${.CURDIR}/tools/install.sh" \
Index: tools/build/options/WITH_LLVM_TARGET_ALL
===================================================================
--- tools/build/options/WITH_LLVM_TARGET_ALL
+++ tools/build/options/WITH_LLVM_TARGET_ALL
@@ -1,2 +1,4 @@
 .\" $FreeBSD$
 Set to build support for all LLVM targets.
+This option is always applied to the bootstrap compiler for buildworld when
+LLVM is used.