Index: head/share/mk/bsd.README
===================================================================
--- head/share/mk/bsd.README
+++ head/share/mk/bsd.README
@@ -17,6 +17,7 @@
 bsd.lib.mk.
 
 bsd.arch.inc.mk		- includes arch-specific Makefile.$arch
+bsd.compat.mk		- definitions for building programs against compat ABIs
 bsd.compiler.mk		- defined based on current compiler
 bsd.confs.mk		- install of configuration files
 bsd.cpu.mk		- sets CPU/arch-related variables (included from sys.mk)
@@ -378,6 +379,10 @@
 MAN		Manual pages.  If no MAN variable is defined,
 		"MAN=${PROG}.1" is assumed. See bsd.man.mk for more details.
 
+NEED_COMPAT	Build and link targeting a compatability ABI or fail if it
+		is not available.  Supported values are "32", "soft", and
+		"any" being a wildcard.
+
 PROG		The name of the program to build.  If not supplied, nothing
 		is built.
 
@@ -439,6 +444,9 @@
 SUBDIR		A list of subdirectories that should be built as well.
 		Each of the targets will execute the same target in the
 		subdirectories.
+
+WANT_COMPAT	Similar to NEED_COMPAT, but build with the base ABI if
+		the specified ABI is not available.
 
 The include file <bsd.prog.mk> includes the file named "../Makefile.inc"
 if it exists, as well as the include file <bsd.man.mk>.
Index: head/share/mk/bsd.compat.mk
===================================================================
--- head/share/mk/bsd.compat.mk
+++ head/share/mk/bsd.compat.mk
@@ -3,18 +3,16 @@
 .if !targets(__<${_this:T}>__)
 __<${_this:T}>__:
 
-# Makefile for the compatibility libraries.
-# - 32-bit compat libraries on MIPS, PowerPC, and AMD64.
-
 # -------------------------------------------------------------------
 # 32 bit world
 .if ${TARGET_ARCH} == "amd64"
+HAS_COMPAT=32
 .if empty(TARGET_CPUTYPE)
 LIB32CPUFLAGS=	-march=i686 -mmmx -msse -msse2
 .else
 LIB32CPUFLAGS=	-march=${TARGET_CPUTYPE}
 .endif
-.if ${WANT_COMPILER_TYPE} == gcc || \
+.if (defined(WANT_COMPILER_TYPE) && ${WANT_COMPILER_TYPE} == gcc) || \
     (defined(X_COMPILER_TYPE) && ${X_COMPILER_TYPE} == gcc)
 .else
 LIB32CPUFLAGS+=	-target x86_64-unknown-freebsd13.0
@@ -27,6 +25,7 @@
 		LD="${XLD} -m elf_i386_fbsd -L${LIBCOMPATTMP}/usr/lib32"
 
 .elif ${TARGET_ARCH} == "powerpc64"
+HAS_COMPAT=32
 .if empty(TARGET_CPUTYPE)
 LIB32CPUFLAGS=	-mcpu=powerpc
 .else
@@ -38,6 +37,7 @@
 		LD="${XLD} -m elf32ppc_fbsd"
 
 .elif ${TARGET_ARCH:Mmips64*} != ""
+HAS_COMPAT=32
 .if ${WANT_COMPILER_TYPE} == gcc || \
     (defined(X_COMPILER_TYPE) && ${X_COMPILER_TYPE} == gcc)
 .if empty(TARGET_CPUTYPE)
@@ -71,13 +71,37 @@
 # -------------------------------------------------------------------
 # soft-fp world
 .if ${TARGET_ARCH:Marmv[67]*} != ""
+HAS_COMPAT=SOFT
 LIBSOFTCFLAGS=        -DCOMPAT_SOFTFP
 LIBSOFTCPUFLAGS= -mfloat-abi=softfp
 LIBSOFTWMAKEENV= CPUTYPE=soft MACHINE=arm MACHINE_ARCH=${TARGET_ARCH}
 LIBSOFTWMAKEFLAGS=        -DCOMPAT_SOFTFP
 .endif
 
+# -------------------------------------------------------------------
+# In the program linking case, select LIBCOMPAT
+.if defined(NEED_COMPAT)
+.ifndef HAS_COMPAT
+.error NEED_COMPAT defined, but no LIBCOMPAT is available
+.elif !${HAS_COMPAT:M${NEED_COMPAT}} && ${NEED_COMPAT} != "any"
+.error NEED_COMPAT (${NEED_COMPAT}) defined, but not in HAS_COMPAT ($HAS_COMPAT)
+.elif ${NEED_COMPAT} == "any"
+.endif
+.ifdef WANT_COMPAT
+.error Both WANT_COMPAT and NEED_COMPAT defined
+.endif
+WANT_COMPAT:=	${NEED_COMPAT}
+.endif
 
+.if defined(HAS_COMPAT) && defined(WANT_COMPAT)
+.if ${WANT_COMPAT} == "any"
+_LIBCOMPAT:=	${HAS_COMPAT:[1]}
+.else
+_LIBCOMPAT:=	${WANT_COMPAT}
+.endif
+.endif
+
+
 # -------------------------------------------------------------------
 # Generic code for each type.
 # Set defaults based on type.
@@ -102,5 +126,11 @@
 # -B is needed to find /usr/lib32/crti.o for GCC and /usr/libsoft/crti.o for
 # Clang/GCC.
 LIBCOMPATCFLAGS+=	-B${LIBCOMPATTMP}/usr/lib${libcompat}
+
+.if defined(WANT_COMPAT)
+LIBDIR_BASE:=	/usr/lib${libcompat}
+_LIB_OBJTOP=	${LIBCOMPAT_OBJTOP}
+CFLAGS+=	${LIBCOMPATCFLAGS}
+.endif
 
 .endif
Index: head/share/mk/bsd.prog.mk
===================================================================
--- head/share/mk/bsd.prog.mk
+++ head/share/mk/bsd.prog.mk
@@ -2,6 +2,7 @@
 # $FreeBSD$
 
 .include <bsd.init.mk>
+.include <bsd.compat.mk>
 .include <bsd.compiler.mk>
 .include <bsd.linker.mk>