Index: Makefile
===================================================================
--- Makefile
+++ Makefile
@@ -4,8 +4,11 @@
 # The user-driven targets are:
 #
 # universe            - *Really* build *everything* (buildworld and
-#                       all kernels on all architectures).  Define the
-#                       MAKE_JUST_KERNELS variable to only build kernels.
+#                       all kernels on all architectures).  Define
+#                       MAKE_JUST_KERNELS to only build kernels,
+#			MAKE_JUST_WORLDS to only build userland, and/or
+#			MAKE_OBSOLETE_GCC to build architectures unsupported
+#			by clang.
 # tinderbox           - Same as universe, but presents a list of failed build
 #                       targets and exits with an error if there were any.
 # buildworld          - Rebuild *everything*, including glue to help do
@@ -481,7 +484,17 @@
 #
 .if make(universe) || make(universe_kernels) || make(tinderbox) || \
     make(targets) || make(universe-toolchain)
-TARGETS?=amd64 arm arm64 i386 mips powerpc riscv sparc64
+#
+# By default, build only the known-good clang-supporting platforms.
+# If MAKE_OBSOLETE_GCC is defined, built all the old GCC architectures.
+# In all cases, if the user specifies TARGETS on the command line,
+# honor that most of all.
+#
+_DEFAULT_TARGETS=amd64 arm arm64 i386
+.if defined(MAKE_OBSOLETE_GCC)
+_DEFAULT_TARGETS+=mips powerpc riscv sparc64
+.endif
+TARGETS?=${_DEFAULT_TARGETS}
 _UNIVERSE_TARGETS=	${TARGETS}
 TARGET_ARCHES_arm?=	arm armv6 armv7
 TARGET_ARCHES_arm64?=	aarch64