new file mode 100644
--- /dev/null
+++ b/m4/mktime.m4
@@ -0,0 +1,75 @@
+#serial 2
+
+dnl From Jim Meyering.
+dnl FIXME: this should migrate into libit.
+
+AC_DEFUN(AM_FUNC_MKTIME,
+[AC_REQUIRE([AC_HEADER_TIME])dnl
+ AC_CHECK_HEADERS(sys/time.h)
+ AC_CACHE_CHECK([for working mktime], am_cv_func_working_mktime,
+  [AC_TRY_RUN(
+changequote(<<, >>)dnl
+<</* Test program from Paul Eggert (eggert@twinsun.com)
+   and Tony Leneis (tony@plaza.ds.adp.com).  */
+#if TIME_WITH_SYS_TIME
+# include <sys/time.h>
+# include <time.h>
+#else
+# if HAVE_SYS_TIME_H
+#  include <sys/time.h>
+# else
+#  include <time.h>
+# endif
+#endif
+
+static time_t time_t_max;
+
+/* Values we'll use to set the TZ environment variable.  */
+static const char *const tz_strings[] = {
+  NULL, "GMT0", "JST-9", "EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
+};
+#define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))
+
+static void
+mktime_test (now)
+     time_t now;
+{
+  if (mktime (localtime (&now)) != now)
+    exit (1);
+  now = time_t_max - now;
+  if (mktime (localtime (&now)) != now)
+    exit (1);
+}
+
+int
+main ()
+{
+  time_t t, delta;
+  int i;
+
+  for (time_t_max = 1; 0 < time_t_max; time_t_max *= 2)
+    continue;
+  time_t_max--;
+  delta = time_t_max / 997; /* a suitable prime number */
+  for (i = 0; i < N_STRINGS; i++)
+    {
+      if (tz_strings[i])
+	putenv (tz_strings[i]);
+
+      for (t = 0; t <= time_t_max - delta; t += delta)
+	mktime_test (t);
+      mktime_test ((time_t) 60 * 60);
+      mktime_test ((time_t) 60 * 60 * 24);
+    }
+  exit (0);
+}
+	      >>,
+changequote([, ])dnl
+	     am_cv_func_working_mktime=yes, am_cv_func_working_mktime=no,
+	     dnl When crosscompiling, assume mktime is missing or broken.
+	     am_cv_func_working_mktime=no)
+  ])
+  if test $am_cv_func_working_mktime = no; then
+    LIBOBJS="$LIBOBJS mktime.o"
+  fi
+])