diff --git a/src/backend/utils/misc/guc-file.l b/src/backend/utils/misc/guc-file.l
index ee38040..d5966a9 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/backend/utils/misc/guc-file.l
@@ -44,6 +44,7 @@ enum {
 static unsigned int ConfigFileLineno;
 static const char *GUC_flex_fatal_errmsg;
 static sigjmp_buf *GUC_flex_fatal_jmp;
+static char	   *tmp_data_directory;
 
 /* flex fails to supply a prototype for yylex, so provide one */
 int GUC_yylex(void);
@@ -122,6 +123,8 @@ ProcessConfigFile(GucContext context)
 	int			i;
 	char		*ErrorConfFile;
 	char		*CallingFileName;
+	char		AutoConfFileName[MAXPGPATH];
+	char		*datadir;
 
 	/*
 	 * Config files are processed on startup (by the postmaster only)
@@ -155,11 +158,28 @@ ProcessConfigFile(GucContext context)
 	 * set till this point, so use ConfigFile path which will be same.
 	 */
 	if (data_directory)
+	{
+		snprintf(AutoConfFileName,sizeof(AutoConfFileName),"%s",
+				 PG_AUTOCONF_FILENAME);
 		CallingFileName = NULL;
+	}
+	else if (tmp_data_directory)
+	{
+		datadir = make_absolute_path(tmp_data_directory);
+		join_path_components(AutoConfFileName, datadir,
+							 PG_AUTOCONF_FILENAME);
+		canonicalize_path(AutoConfFileName);
+		free(datadir);
+		CallingFileName = NULL;
+	}
 	else
+	{
+		snprintf(AutoConfFileName,sizeof(AutoConfFileName),"%s",
+				 PG_AUTOCONF_FILENAME);
 		CallingFileName = ConfigFileName;
+	}
 
-	if (!ParseConfigFile(PG_AUTOCONF_FILENAME, CallingFileName, false, 0, elevel, &head, &tail))
+	if (!ParseConfigFile(AutoConfFileName, CallingFileName, false, 0, elevel, &head, &tail))
 	{
 		/* Syntax error(s) detected in the file, so bail out */
 		error = true;
@@ -654,6 +674,15 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		}
 		else
 		{
+			/*
+			 * In case of postmaster start for processing PG_AUTOCONF_FILENAME,
+			 * we need to know the value of data_directory which is available
+			 * only after processing of configuration files.  Store it's value
+			 * for use till data_directory is set.
+			 */
+			if (guc_name_compare(opt_name, "data_directory") == 0)
+				tmp_data_directory = opt_value;
+
 			/* ordinary variable, append to list */
 			item = palloc(sizeof *item);
 			item->name = opt_name;