diff --git a/lib/getugroups.c b/lib/getugroups.c

index 299bae6..8ece29b 100644

--- a/lib/getugroups.c

+++ b/lib/getugroups.c

@@ -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 <errno.h>

@@ -123,3 +126,4 @@ getugroups (int maxcount, gid_t *grouplist, char const *username,

 }

 #endif /* HAVE_GRP_H */

+#endif	/* have getgrouplist */

diff --git a/lib/mgetgroups.c b/lib/mgetgroups.c

index 76474c2..0a9d221 100644

--- a/lib/mgetgroups.c

+++ b/lib/mgetgroups.c

@@ -115,9 +115,17 @@ mgetgroups (char const *username, gid_t gid, gid_t **groups)

   /* else no username, so fall through and use getgroups. */

 #endif

-  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 because there is no supplemental

      group support, then return an array containing just GID.

@@ -139,10 +147,25 @@ mgetgroups (char const *username, gid_t gid, gid_t **groups)

   if (g == NULL)

     return -1;

-  ng = (username

-        ? getugroups (max_n_groups, g, username, gid)

-        : getgroups (max_n_groups - (gid != (gid_t) -1),

-                                g + (gid != (gid_t) -1)));

+  if (!username)

+    ng = getgroups (max_n_groups - (gid != (gid_t)-1), g + (gid != (gid_t)-1));

+  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 --git a/m4/jm-macros.m4 b/m4/jm-macros.m4

index 62777c7..5180243 100644

--- a/m4/jm-macros.m4

+++ b/m4/jm-macros.m4

@@ -78,6 +78,7 @@ AC_DEFUN([coreutils_MACROS],

     fchown \

     fchmod \

     ftruncate \

+    getgrouplist \

     iswspace \

     mkfifo \

     mbrlen \