--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2009-12-23  Eric Blake  <ebb9@byu.net>
 
+	va-args: new module
+	* modules/va-args: New file.
+	* m4/va-args.m4 (gl_VA_ARGS): Likewise.
+	* MODULES.html.sh (Core language properties): Mention it.
+
 	gnulib-common: prefer _GL_UNUSED over _UNUSED_PARAMETER_
 	* m4/gnulib-common.m4 (gl_COMMON): Create a more-appropriately
 	named alias for __attribute__((__unused__)).

--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2000,6 +2000,7 @@
   func_module func
   func_module inline
   func_module longlong
+  func_module va-args
   func_module vararrays
   func_end_table
 

new file mode 100644
--- /dev/null
+++ b/m4/va-args.m4
@@ -0,0 +1,25 @@
+# va-args.m4 serial 1
+dnl Copyright (C) 2009 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Test for variadic macro support.
+dnl Define HAVE_VA_ARGS if macros can use __VA_ARGS__.
+AC_DEFUN([gl_VA_ARGS],
+[
+  AC_CACHE_CHECK([whether the preprocessor allows variadic macros],
+    [gl_cv_c_va_args],
+    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+       #include <stdio.h>
+       #define a(func, arg, ...) func (arg, __VA_ARGS__)
+       #define b(...) a (__VA_ARGS__)
+      ]], [[b (printf, "%s", "test");]])],
+      [gl_cv_c_va_args=yes], [gl_cv_c_va_args=no])
+    ])
+  if test $gl_cv_c_va_args = yes; then
+    AC_DEFINE([HAVE_VA_ARGS], [1],
+      [Define to 1 if the preprocessor supports variadic macros and
+       __VA_ARGS__.])
+  fi
+])

new file mode 100644
--- /dev/null
+++ b/modules/va-args
@@ -0,0 +1,20 @@
+Description:
+Detect whether the preprocessor supports C99 variadic macros and __VA_ARGS__.
+
+Files:
+m4/va-args.m4
+
+Depends-on:
+
+configure.ac:
+gl_VA_ARGS
+
+Makefile.am:
+
+Include:
+
+License:
+LGPL
+
+Maintainer:
+Eric Blake