diff --git a/xargs/xargs.1 b/xargs/xargs.1
index ebcb1e0..b216c61 100644
--- a/xargs/xargs.1
+++ b/xargs/xargs.1
@@ -65,7 +65,10 @@ than there were items in the input.  This will normally have
 significant performance benefits.  Some commands can usefully be
 executed in parallel too; see the
 .B \-P
-option.
+option.  To help commands form easily sequenced output file names, GNU
+.B xargs
+exports to commands an environment variable XARGS_SEQ containing the
+invocation number (padded with leading zeros).
 .P
 Because Unix filenames can contain blanks and newlines, this default
 behaviour is often problematic; filenames containing blanks
diff --git a/xargs/xargs.c b/xargs/xargs.c
index 5fd93cd..b634461 100644
--- a/xargs/xargs.c
+++ b/xargs/xargs.c
@@ -369,7 +369,7 @@ main (int argc, char **argv)
   int (*read_args) (void) = read_line;
   void (*act_on_init_result)(void) = noop;
   enum BC_INIT_STATUS bcstatus;
-  enum { XARGS_POSIX_HEADROOM = 2048u };
+  enum { XARGS_POSIX_HEADROOM = 2076u };  /* 2048 +28 for $XARGS_SEQ usage */
   struct sigaction sigact;
 
   if (argv[0])
@@ -1155,6 +1155,7 @@ prep_child_for_exec (void)
 static int
 xargs_do_exec (struct buildcmd_control *ctl, void *usercontext, int argc, char **argv)
 {
+  static unsigned int xargs_seq_num;
   pid_t child;
   int fd[2];
   int buf;
@@ -1164,6 +1165,7 @@ xargs_do_exec (struct buildcmd_control *ctl, void *usercontext, int argc, char *
   (void) argc;
   (void) usercontext;
 
+  xargs_seq_num++;              /* count command invocations for user */
   if (!query_before_executing || print_args (true))
     {
       if (proc_max)
@@ -1203,6 +1205,12 @@ xargs_do_exec (struct buildcmd_control *ctl, void *usercontext, int argc, char *
 
 	case 0:		/* Child.  */
 	  {
+            char env_var[24];   /* For <=9 digit numbers max is 10+10 bytes */
+            sprintf(env_var, "XARGS_SEQ=%09u", xargs_seq_num);
+            putenv(env_var);    /* export XARGS_SEQ; ENOMEM failure is
+                                 * conceivable, but neither failure nor falling
+                                 * back makes much sense in that situation. */
+
 	    close (fd[0]);
 	    child_error = EXIT_SUCCESS;