--- a/configure.in	Fri Dec 16 12:43:51 2011 +0200
+++ b/configure.in	Fri Dec 16 12:50:53 2011 +0200
@@ -33,6 +33,7 @@
 AS_HELP_STRING([--enable-devel-checks], [Enable some extra expensive checks for developers]),
 	if test x$enableval = xyes; then
 		AC_DEFINE(DEBUG,, Build with extra debugging checks)
+		want_devel_checks=yes
 	fi)
 
 AC_ARG_ENABLE(asserts,
@@ -319,6 +320,12 @@
 	  CFLAGS="$old_cflags"
 	])
 fi
+if $CC -dM -E -x c /dev/null | grep __clang__ > /dev/null 2>&1; then
+  # clang specific options
+  if test "$want_devel_checks" = "yes"; then
+    CFLAGS="$CFLAGS -fcatch-undefined-behavior -ftrapv"
+  fi
+fi
 
 dnl **
 dnl ** just some generic stuff...