diff --git a/sys/alpha/include/stdarg.h b/sys/alpha/include/stdarg.h
index b14b68605bfa..bd67f1f2cf76 100644
--- a/sys/alpha/include/stdarg.h
+++ b/sys/alpha/include/stdarg.h
@@ -36,12 +36,16 @@
  * $FreeBSD$
  */
 
-#ifndef _ALPHA_STDARG_H_
-#define	_ALPHA_STDARG_H_
+#ifndef _MACHINE_STDARG_H_
+#define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
-typedef __va_list	va_list;
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
+typedef	__va_list	va_list;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ == 2 && __GNUC_MINOR__ > 95 || __GNUC__ >= 3)
 
@@ -51,8 +55,10 @@ typedef __va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)
@@ -83,4 +89,4 @@ typedef __va_list	va_list;
 
 #endif /* __GNUC__ post GCC 2.95 */
 
-#endif /* !_ALPHA_STDARG_H_ */
+#endif /* !_MACHINE_STDARG_H_ */
diff --git a/sys/amd64/include/stdarg.h b/sys/amd64/include/stdarg.h
index b7b1954e7bb9..53985af466a6 100644
--- a/sys/amd64/include/stdarg.h
+++ b/sys/amd64/include/stdarg.h
@@ -31,9 +31,13 @@
 #ifndef _MACHINE_STDARG_H_
 #define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
 typedef	__va_list	va_list;
+#endif
 
 #define	va_start(ap, last) \
 	__builtin_stdarg_start((ap), (last))
@@ -41,8 +45,10 @@ typedef	__va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)
diff --git a/sys/i386/include/stdarg.h b/sys/i386/include/stdarg.h
index 3ce2f376b387..246a991f814d 100644
--- a/sys/i386/include/stdarg.h
+++ b/sys/i386/include/stdarg.h
@@ -35,12 +35,16 @@
  * $FreeBSD$
  */
 
-#ifndef _STDARG_H_
-#define	_STDARG_H_
+#ifndef _MACHINE_STDARG_H_
+#define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
-typedef __va_list	va_list;
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
+typedef	__va_list	va_list;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ == 2 && __GNUC_MINOR__ > 95 || __GNUC__ >= 3)
 
@@ -50,8 +54,10 @@ typedef __va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)
@@ -77,4 +83,4 @@ typedef __va_list	va_list;
 
 #endif /* __GNUC__ post GCC 2.95 */
 
-#endif /* !_STDARG_H_ */
+#endif /* !_MACHINE_STDARG_H_ */
diff --git a/sys/ia64/include/stdarg.h b/sys/ia64/include/stdarg.h
index df9725d4c829..51dde800de58 100644
--- a/sys/ia64/include/stdarg.h
+++ b/sys/ia64/include/stdarg.h
@@ -38,9 +38,13 @@
 #ifndef _MACHINE_STDARG_H_
 #define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
 typedef	__va_list	va_list;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ == 2 && __GNUC_MINOR__ > 95 || __GNUC__ >= 3)
 
@@ -50,8 +54,10 @@ typedef	__va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)
diff --git a/sys/powerpc/include/stdarg.h b/sys/powerpc/include/stdarg.h
index 5b5bcb38db12..75a7bd43aa8c 100644
--- a/sys/powerpc/include/stdarg.h
+++ b/sys/powerpc/include/stdarg.h
@@ -28,12 +28,16 @@
  * $FreeBSD$
  */
 
-#ifndef _POWERPC_STDARG_H_
-#define	_POWERPC_STDARG_H_
+#ifndef _MACHINE_STDARG_H_
+#define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
 typedef	__va_list	va_list;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ == 2 && __GNUC_MINOR__ > 95 || __GNUC__ >= 3)
 
@@ -43,8 +47,10 @@ typedef	__va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)
@@ -127,13 +133,15 @@ typedef	__va_list	va_list;
 
 #define	va_end(ap)	
 
+#if __ISO_C_VISIBLE >= 1999
 #if !defined(_ANSI_SOURCE) &&						\
     (!defined(_POSIX_C_SOURCE) && !defined(_XOPEN_SOURCE) ||		\
      defined(_ISOC99_SOURCE) || (__STDC_VERSION__ - 0) >= 199901L)
 #define	va_copy(dest, src)						\
 	((dest) = (src))
 #endif
+#endif
 
 #endif /* __GNUC__ post GCC 2.95 */
 
-#endif /* _POWERPC_STDARG_H_ */
+#endif /* _MACHINE_STDARG_H_ */
diff --git a/sys/sparc64/include/stdarg.h b/sys/sparc64/include/stdarg.h
index b148b71891a9..3f8b615334e2 100644
--- a/sys/sparc64/include/stdarg.h
+++ b/sys/sparc64/include/stdarg.h
@@ -41,9 +41,13 @@
 #ifndef _MACHINE_STDARG_H_
 #define	_MACHINE_STDARG_H_
 
+#include <sys/cdefs.h>
 #include <sys/_types.h>
 
+#ifndef _VA_LIST_DECLARED
+#define	_VA_LIST_DECLARED
 typedef	__va_list	va_list;
+#endif
 
 #if defined(__GNUC__) && (__GNUC__ == 2 && __GNUC_MINOR__ > 95 || __GNUC__ >= 3)
 
@@ -53,8 +57,10 @@ typedef	__va_list	va_list;
 #define	va_arg(ap, type) \
 	__builtin_va_arg((ap), type)
 
+#if __ISO_C_VISIBLE >= 1999
 #define	va_copy(dest, src) \
 	__builtin_va_copy((dest), (src))
+#endif
 
 #define	va_end(ap) \
 	__builtin_va_end(ap)