Index: head/gnu/usr.bin/binutils/Makefile
===================================================================
--- head/gnu/usr.bin/binutils/Makefile
+++ head/gnu/usr.bin/binutils/Makefile
@@ -8,8 +8,14 @@
 
 SUBDIR.${MK_BINUTILS}+=	doc
 SUBDIR.${MK_BINUTILS}+=	libbinutils
-SUBDIR.${MK_BINUTILS}+=	as
 SUBDIR.${MK_BINUTILS}+=	objdump
+
+# GNU as is used on x86 only, for a few files that cannot be assembled by
+# Clang IAS. Other archs either use Clang IAS for every assembly file, or
+# use external toolchain.
+.if ${TARGET} == "amd64" || ${TARGET} == "i386"
+SUBDIR.${MK_BINUTILS}+=	as
+.endif
 
 # All archs except powerpc either use lld or require external toolchain.
 # powerpc still needs binutils ld to link 32-bit binaries.
Index: head/tools/build/options/WITH_BINUTILS
===================================================================
--- head/tools/build/options/WITH_BINUTILS
+++ head/tools/build/options/WITH_BINUTILS
@@ -1,8 +1,8 @@
 .\" $FreeBSD$
-Set to build and install GNU
-.Xr as 1 ,
+Build and install GNU
+.Xr as 1
+on i386 and amd64,
 .Xr objdump 1 ,
-and, on powerpc,
+and
 .Xr ld.bfd 1
-as part
-of the normal system build.
+on powerpc as part of the normal system build.
Index: head/tools/build/options/WITH_BINUTILS_BOOTSTRAP
===================================================================
--- head/tools/build/options/WITH_BINUTILS_BOOTSTRAP
+++ head/tools/build/options/WITH_BINUTILS_BOOTSTRAP
@@ -1,3 +1,3 @@
 .\" $FreeBSD$
-Set build binutils (as, objdump, and on powerpc ld)
+Build binutils (as on i386 and amd64, objdump, and ld on powerpc)
 as part of the bootstrap process.