diff -urp coreutils-6.10-orig/lib/getugroups.c coreutils-6.10/lib/getugroups.c
--- coreutils-6.10-orig/lib/getugroups.c	2007-10-17 15:47:25.000000000 +0200
+++ coreutils-6.10/lib/getugroups.c	2008-01-24 16:37:04.000000000 +0100
@@ -19,6 +19,9 @@
 
 #include <config.h>
 
+/* We do not need this code if getgrouplist(3) is available.  */
+#ifndef HAVE_GETGROUPLIST
+
 #include "getugroups.h"
 
 #include <stdio.h> /* grp.h on alpha OSF1 V2.0 uses "FILE *". */
@@ -114,3 +117,4 @@ getugroups (int maxcount, GETGROUPS_T *g
 
   return count;
 }
+#endif	/* have getgrouplist */
diff -urp coreutils-6.10-orig/lib/mgetgroups.c coreutils-6.10/lib/mgetgroups.c
--- coreutils-6.10-orig/lib/mgetgroups.c	2007-11-25 14:23:31.000000000 +0100
+++ coreutils-6.10/lib/mgetgroups.c	2008-01-24 16:41:15.000000000 +0100
@@ -43,9 +43,17 @@ mgetgroups (const char *username, gid_t 
   int ng;
   GETGROUPS_T *g;
 
-  max_n_groups = (username
-		  ? getugroups (0, NULL, username, gid)
-		  : getgroups (0, NULL));
+    if (!username)
+      max_n_groups = getgroups(0, NULL);
+  else 
+   {
+#ifdef HAVE_GETGROUPLIST
+      max_n_groups = 0;
+      getgrouplist (username, gid, NULL, &max_n_groups);
+#else
+      max_n_groups = getugroups (0, NULL, username, gid);
+#endif
+   }
 
   /* If we failed to count groups with NULL for a buffer,
      try again with a non-NULL one, just in case.  */
@@ -62,9 +70,25 @@ mgetgroups (const char *username, gid_t 
   if (g == NULL)
     return -1;
 
-  ng = (username
-	? getugroups (max_n_groups, g, username, gid)
-	: getgroups (max_n_groups, g));
+  if (!username)
+    ng = getgroups (max_n_groups, g);
+  else
+    {
+#ifdef HAVE_GETGROUPLIST
+	  int e;
+	  ng = max_n_groups;
+	  while ((e = getgrouplist (username, gid, g, &ng)) == -1
+		 && ng > max_n_groups)
+	    {
+	      max_n_groups = ng;
+	      g = xrealloc (g, max_n_groups * sizeof (GETGROUPS_T));
+	    }
+	  if (e == -1)
+	    ng = -1;
+#else
+	  ng = getugroups (max_n_groups, g, username, gid);
+#endif
+    }
 
   if (ng < 0)
     {
diff -urp coreutils-6.10-orig/m4/jm-macros.m4 coreutils-6.10/m4/jm-macros.m4
--- coreutils-6.10-orig/m4/jm-macros.m4	2007-11-25 14:23:31.000000000 +0100
+++ coreutils-6.10/m4/jm-macros.m4	2008-01-24 16:42:00.000000000 +0100
@@ -52,6 +52,7 @@ AC_DEFUN([coreutils_MACROS],
     fchown \
     fchmod \
     ftruncate \
+    getgrouplist \
     iswspace \
     mkfifo \
     mbrlen \