Index: Mk/Scripts/set-late-configure-args.sh
===================================================================
--- /dev/null
+++ Mk/Scripts/set-late-configure-args.sh
@@ -0,0 +1,79 @@
+#!/bin/sh
+# ports/Mk/Scripts/set-late-configure-args.sh - called from ports/Mk/bsd.stage.mk
+# $FreeBSD$
+#
+# MAINTAINER: portmgr@FreeBSD.org
+#
+# Determine what features configure supports and set some wanted defaults.
+
+
+set -e
+
+. "${dp_SCRIPTSDIR}/functions.sh"
+
+validate_env \
+    dp_CONFIGURE_ARGS \
+    dp_CONFIGURE_CMD \
+    dp_CONFIGURE_TARGET \
+    dp_GNU_CONFIGURE_MANPREFIX \
+    dp_GNU_CONFIGURE_PREFIX \
+    dp_INFO_PATH \
+    dp_INFO_SUBDIR \
+    dp_MAKE_JOBS_NUMBER \
+    # For sorting with previous trailing backslash.
+
+[ -n "${DEBUG_MK_SCRIPTS}" -o \
+    -n "${DEBUG_MK_SCRIPTS_SET_LATE_CONFIGURE_ARGS}" ] && set -x
+
+set -u
+
+append()
+{
+	configure_args="${configure_args}${configure_args:+ }$@"
+}
+
+configure_args=
+
+# Parse --version for --build behavior
+want_build=1
+while read line; do
+	case "${line}" in
+	*[aA]utoconf*2.13*|*Unrecognized\ option*)
+		want_build=0
+		break
+		;;
+	esac
+done <<-EOF
+$("${dp_CONFIGURE_CMD}" --version 2>&1)
+EOF
+if [ ${want_build} -eq 1 ]; then
+	append "--build=${dp_CONFIGURE_TARGET}"
+else
+	append "${dp_CONFIGURE_TARGET}"
+fi
+
+# Parse --help
+while read line; do
+	case "${line}" in
+	--disable-silent-rules*)
+		append "--disable-silent-rules"
+		;;
+	--enable-jobserver\[*#\]*)
+		append "--enable-jobserver=${dp_MAKE_JOBS_NUMBER}"
+		;;
+	--infodir*)
+		append "--infodir=${dp_GNU_CONFIGURE_PREFIX}/${dp_INFO_PATH}${dp_INFO_SUBDIR:+/}${dp_INFO_SUBDIR}"
+		;;
+	--localstatedir*)
+		# Only add if not already present.
+		[ -n "${dp_CONFIGURE_ARGS%%*--localstatedir=*}" ] &&
+		    append "--localstatedir=/var"
+		;;
+	--mandir*)
+		append "--mandir=${dp_GNU_CONFIGURE_MANPREFIX}/man"
+		;;
+	esac
+done <<-EOF
+$("${dp_CONFIGURE_CMD}" --help 2>&1)
+EOF
+echo "${configure_args}"
Index: Mk/bsd.port.mk
===================================================================
--- Mk/bsd.port.mk
+++ Mk/bsd.port.mk
@@ -2537,28 +2537,17 @@
 HAS_CONFIGURE=		yes
 
 SET_LATE_CONFIGURE_ARGS= \
-     _LATE_CONFIGURE_ARGS="" ; \
-	if [ -z "${CONFIGURE_ARGS:M--localstatedir=*:Q}" ] && \
-	   ${CONFIGURE_CMD} --help 2>&1 | ${GREP} -- --localstatedir > /dev/null; then \
-	    _LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --localstatedir=/var" ; \
-	fi ; \
-	if [ ! -z "`${CONFIGURE_CMD} --help 2>&1 | ${GREP} -- '--mandir'`" ]; then \
-	    _LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --mandir=${GNU_CONFIGURE_MANPREFIX}/man" ; \
-	fi ; \
-	if [ ! -z "`${CONFIGURE_CMD} --help 2>&1 | ${GREP} -- '--disable-silent-rules'`" ]; then \
-	    _LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --disable-silent-rules" ; \
-	fi ; \
-	if [ ! -z "`${CONFIGURE_CMD} --help 2>&1 | ${GREP} -- '--enable-jobserver\[.*\#\]'`" ]; then \
-	    _LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --enable-jobserver=${MAKE_JOBS_NUMBER}" ; \
-	fi ; \
-	if [ ! -z "`${CONFIGURE_CMD} --help 2>&1 | ${GREP} -- '--infodir'`" ]; then \
-	    _LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --infodir=${GNU_CONFIGURE_PREFIX}/${INFO_PATH}/${INFO_SUBDIR}" ; \
-	fi ; \
-	if [ -z "`${CONFIGURE_CMD} --version 2>&1 | ${EGREP} -i '(autoconf.*2\.13|Unrecognized option)'`" ]; then \
-		_LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} --build=${CONFIGURE_TARGET}" ; \
-	else \
-		_LATE_CONFIGURE_ARGS="$${_LATE_CONFIGURE_ARGS} ${CONFIGURE_TARGET}" ; \
-	fi ;
+	_LATE_CONFIGURE_ARGS=`${SETENV} \
+							dp_SCRIPTSDIR="${SCRIPTSDIR}" \
+							dp_CONFIGURE_ARGS="${CONFIGURE_ARGS}" \
+							dp_CONFIGURE_CMD="${CONFIGURE_CMD}" \
+							dp_CONFIGURE_TARGET="${CONFIGURE_TARGET}" \
+							dp_GNU_CONFIGURE_MANPREFIX="${GNU_CONFIGURE_MANPREFIX}" \
+							dp_GNU_CONFIGURE_PREFIX="${GNU_CONFIGURE_PREFIX}" \
+							dp_INFO_PATH="${INFO_PATH}" \
+							dp_INFO_SUBDIR="${INFO_SUBDIR}" \
+							dp_MAKE_JOBS_NUMBER="${MAKE_JOBS_NUMBER}" \
+							${SH} ${SCRIPTSDIR}/set-late-configure-args.sh`;
 .endif
 
 # Passed to most of script invocations