--- a/configure.in
+++ b/configure.in
@@ -267,11 +267,9 @@
     cflagspat="$cflagspat;s|"`eval echo '"'"${debugflags}"'"' | sed 's/[[][|.*]]/\\&/g;s/^ */ /;s/ *$/ /'`'| |g'
 test -z "warnflags" ||
     cflagspat="$cflagspat;s|"`eval echo '"'"${warnflags}"'"' | sed 's/[[][|.*]]/\\&/g;s/^ */ /;s/ *$/ /'`'| |g'
-if test -z "${CFLAGS+set}"; then
-    cflags=`echo " $cflags " | sed "$cflagspat;s/^ *//;s/ *$//"`
-    orig_cflags="$cflags"
-    cflags="$cflags "'${optflags} ${debugflags} ${warnflags}'
-fi
+cflags=`echo " $cflags " | sed "$cflagspat;s/^ *//;s/ *$//"`
+orig_cflags="$cflags"
+cflags="$cflags "'${optflags} ${debugflags} ${warnflags}'
 if test -z "${CXXFLAGS+set}"; then
     cxxflags=`echo " $cxxflags " | sed "$cflagspat;s/^ *//;s/ *$//"`
     orig_cxxflags="$cxxflags"
@@ -511,7 +509,8 @@
     ])
 fi

-test -z "${ac_env_CFLAGS_set}" -a -n "${cflags+set}" && eval CFLAGS="\"$cflags $ARCH_FLAG\""
+test -z "${ac_env_CFLAGS_set}" && CFLAGS="$ARCH_FLAG"
+test -n "${cflags:+set}" && eval CFLAGS="\"$cflags\${CFLAGS:+ $CFLAGS}\""
 test -z "${ac_env_CXXFLAGS_set}" -a -n "${cxxflags+set}" && eval CXXFLAGS="\"$cxxflags $ARCH_FLAG\""

 dnl check for large file stuff