Index: gnu/usr.bin/binutils/Makefile
===================================================================
--- gnu/usr.bin/binutils/Makefile
+++ gnu/usr.bin/binutils/Makefile
@@ -8,9 +8,14 @@
 
 SUBDIR.${MK_BINUTILS}+=	doc
 SUBDIR.${MK_BINUTILS}+=	libbinutils
-SUBDIR.${MK_BINUTILS}+=	as
 SUBDIR.${MK_BINUTILS}+=	objdump
 
+# GNU as is used on a subset of archs - others use Clang's integrated
+# assembler or require external toolchain.
+.if ${TARGET} == "amd64" || ${TARGET} == "i386" || ${TARGET} == "powerpc"
+SUBDIR.${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.
 .if ${TARGET} == "powerpc"
Index: tools/build/options/WITH_BINUTILS
===================================================================
--- tools/build/options/WITH_BINUTILS
+++ tools/build/options/WITH_BINUTILS
@@ -1,6 +1,7 @@
 .\" $FreeBSD$
-Set to build and install GNU
-.Xr as 1 ,
+Build and install GNU
+.Xr as 1
+(on some CPU architectures),
 .Xr objdump 1 ,
 and, on powerpc,
 .Xr ld.bfd 1
Index: tools/build/options/WITH_BINUTILS_BOOTSTRAP
===================================================================
--- tools/build/options/WITH_BINUTILS_BOOTSTRAP
+++ tools/build/options/WITH_BINUTILS_BOOTSTRAP
@@ -1,3 +1,3 @@
 .\" $FreeBSD$
-Set build binutils (as, objdump, and on powerpc ld)
+Build binutils (as on some CPU architectures, objdump, and on powerpc ld)
 as part of the bootstrap process.