Index: nslcd/cfg.c
===================================================================
--- nslcd/cfg.c	(revision 1074)
+++ nslcd/cfg.c	(working copy)
@@ -118,6 +118,7 @@
 #endif /* LDAP_OPT_X_TLS */
   cfg->ldc_restart=1;
   cfg->ldc_pagesize=0;
+  cfg->ldc_nss_initgroups_ignoreusers=NULL;
 }
 
 /* simple strdup wrapper */
@@ -679,6 +680,50 @@
   }
 }
 
+/* this function modifies the statement argument passed */
+static void parse_nss_initgroups_ignoreusers_statement(
+              const char *filename,int lnr,const char *keyword,
+              char *line,struct ldap_config *cfg)
+{
+  char token[MAX_LINE_LENGTH];
+  char *username,*next;
+  struct passwd *pwent;
+  check_argumentcount(filename,lnr,keyword,(line!=NULL)&&(*line!='\0'));
+  if (cfg->ldc_nss_initgroups_ignoreusers==NULL)
+    cfg->ldc_nss_initgroups_ignoreusers=set_new();
+  while (get_token(&line,token,sizeof(token))!=NULL)
+  {
+    if (strcasecmp(token,"alllocal")==0)
+    {
+      /* go over all users (this will work because nslcd is not yet running) */
+      setpwent();
+      while ((pwent=getpwent())!=NULL)
+        set_add(cfg->ldc_nss_initgroups_ignoreusers,pwent->pw_name);
+      endpwent();
+    }
+    else
+    {
+      next=token;
+      while (*next!='\0')
+      {
+        username=next;
+        /* find the end of the current username */
+        while ((*next!='\0')&&(*next!=',')) next++;
+        if (*next==',')
+        {
+          *next='\0';
+          next++;
+        }
+        /* check if user exists (but add anyway) */
+        pwent=getpwnam(username);
+        if (pwent==NULL)
+          log_log(LOG_ERR,"%s:%d: user '%s' does not exist",filename,lnr,username);
+        set_add(cfg->ldc_nss_initgroups_ignoreusers,username);
+      }
+    }
+  }
+}
+
 static void cfg_read(const char *filename,struct ldap_config *cfg)
 {
   FILE *fp;
@@ -971,6 +1016,10 @@
       get_int(filename,lnr,keyword,&line,&cfg->ldc_pagesize);
       get_eol(filename,lnr,keyword,&line);
     }
+    else if (strcasecmp(keyword,"nss_initgroups_ignoreusers")==0)
+    {
+      parse_nss_initgroups_ignoreusers_statement(filename,lnr,keyword,line,cfg);
+    }
 #ifdef ENABLE_CONFIGFILE_CHECKING
     /* fallthrough */
     else
Index: nslcd/cfg.h
===================================================================
--- nslcd/cfg.h	(revision 1074)
+++ nslcd/cfg.h	(working copy)
@@ -32,6 +32,7 @@
 #include <ldap.h>
 
 #include "compat/attrs.h"
+#include "common/set.h"
 
 /* values for uid and gid */
 #define NOUID ((gid_t)-1)
@@ -132,6 +133,9 @@
   int ldc_restart;
   /* set to a greater than 0 to enable handling of paged results with the specified size */
   int ldc_pagesize;
+  /* the users for which no initgroups() searches should be done
+     Note: because we use a set here comparisons will be case-insensitive */
+  SET *ldc_nss_initgroups_ignoreusers;
 };
 
 /* this is a pointer to the global configuration, it should be available
Index: nslcd/group.c
===================================================================
--- nslcd/group.c	(revision 1074)
+++ nslcd/group.c	(working copy)
@@ -314,6 +314,15 @@
   if (!isvalidname(name)) {
     log_log(LOG_WARNING,"nslcd_group_bymember(%s): invalid user name",name);
     return -1;
+  }
+  if ((nslcd_cfg->ldc_nss_initgroups_ignoreusers!=NULL)&&
+      set_contains(nslcd_cfg->ldc_nss_initgroups_ignoreusers,name))
+  {
+    /* just end the request, returning no results */
+    WRITE_INT32(fp,NSLCD_VERSION);
+    WRITE_INT32(fp,NSLCD_ACTION_GROUP_BYMEMBER);
+    WRITE_INT32(fp,NSLCD_RESULT_END);
+    return 0;
   },
   log_log(LOG_DEBUG,"nslcd_group_bymember(%s)",name);,
   NSLCD_ACTION_GROUP_BYMEMBER,
Index: man/nslcd.conf.5.xml
===================================================================
--- man/nslcd.conf.5.xml	(revision 1075)
+++ man/nslcd.conf.5.xml	(working copy)
@@ -625,6 +625,23 @@
      </listitem>
     </varlistentry>
 
+    <varlistentry>
+     <term><option>nss_initgroups_ignoreusers</option> user1,user2,...</term>
+     <listitem>
+      <para>
+       This option prevents group membership lookups through
+       <acronym>LDAP</acronym> for the specified users. This can be useful
+       in case of unavailability of the <acronym>LDAP</acronym> server.
+       This option may be specified multiple times.
+      </para>
+      <para>
+       Alternatively, the value <emphasis remap="I">ALLLOCAL</emphasis> may be
+       used. With that value nslcd builds a full list of
+       non-<acronym>LDAP</acronym> users on startup.
+      </para>
+     </listitem>
+    </varlistentry>
+
    </variablelist>
   </refsect2>