diff --git a/mysql/config/ac-macros/misc.m4 b/mysql/config/ac-macros/misc.m4
index 9c7b9ae..93c27c4 100644
--- a/mysql/config/ac-macros/misc.m4
+++ b/mysql/config/ac-macros/misc.m4
@@ -717,6 +717,28 @@ dnl END OF MYSQL_CHECK_MAX_INDEXES SECTION
 dnl ---------------------------------------------------------------------------
 
 
+dnl ---------------------------------------------------------------------------
+dnl Macro: MYSQL_CHECK_USERNAME_LENGTH
+dnl Sets USERNAME_LENGTH when --with-username-length is used
+dnl ---------------------------------------------------------------------------
+AC_DEFUN([MYSQL_CHECK_USERNAME_LENGTH], [
+  AC_ARG_WITH([username-length],
+              [
+  --with-username-length       Maximum username length, default 16],
+              [USERNAME_LENGTH="$withval"],
+              [USERNAME_LENGTH=16])
+  AC_MSG_CHECKING([username length])
+
+  AC_DEFINE_UNQUOTED([USERNAME_LENGTH], [$USERNAME_LENGTH], [Maximum username length])
+  AC_MSG_RESULT([$USERNAME_LENGTH])
+  AC_SUBST(USERNAME_LENGTH)
+
+])
+dnl ---------------------------------------------------------------------------
+dnl END OF MYSQL_CHECK_USERNAME_LENGTH SECTION
+dnl ---------------------------------------------------------------------------
+
+
 dnl MYSQL_NEEDS_MYSYS_NEW
 AC_DEFUN([MYSQL_NEEDS_MYSYS_NEW],
 [AC_CACHE_CHECK([needs mysys_new helpers], mysql_use_mysys_new,
diff --git a/mysql/configure.in b/mysql/configure.in
index 05a6620..d3508da 100644
--- a/mysql/configure.in
+++ b/mysql/configure.in
@@ -2571,6 +2571,7 @@ AC_SUBST(readline_h_ln_cmd)
 
 MYSQL_CHECK_BIG_TABLES
 MYSQL_CHECK_MAX_INDEXES
+MYSQL_CHECK_USERNAME_LENGTH
 MYSQL_CHECK_BDB
 MYSQL_CHECK_INNODB
 MYSQL_CHECK_EXAMPLEDB
diff --git a/mysql/include/mysql_com.h b/mysql/include/mysql_com.h
index 889579e..6c8cebf 100644
--- a/mysql/include/mysql_com.h
+++ b/mysql/include/mysql_com.h
@@ -22,7 +22,6 @@
 
 #define NAME_LEN	64		/* Field/table name length */
 #define HOSTNAME_LENGTH 60
-#define USERNAME_LENGTH 16
 #define SERVER_VERSION_LENGTH 60
 #define SQLSTATE_LENGTH 5
 
diff --git a/mysql/scripts/Makefile.am b/mysql/scripts/Makefile.am
index 161c8a5..c3442a2 100644
--- a/mysql/scripts/Makefile.am
+++ b/mysql/scripts/Makefile.am
@@ -25,6 +25,7 @@ bin_SCRIPTS =		@server_scripts@ \
 			mysql_config \
 			mysql_fix_privilege_tables \
 			mysql_fix_extensions \
+			mysql_fix_username_length \
 			mysql_setpermission \
 			mysql_secure_installation \
 			mysql_zap \
@@ -78,7 +79,8 @@ dist_pkgdata_DATA =	fill_help_tables.sql \
 			mysql_fix_privilege_tables.sql \
 			mysql_system_tables.sql \
 			mysql_system_tables_data.sql \
-			mysql_test_data_timezone.sql
+			mysql_test_data_timezone.sql \
+			mysql_fix_username_length.sql
 
 CLEANFILES =		@server_scripts@ \
 			make_binary_distribution \
@@ -87,6 +89,7 @@ CLEANFILES =		@server_scripts@ \
 			mysql_config \
 			mysql_fix_privilege_tables \
 			mysql_fix_extensions \
+			mysql_fix_username_length \
 			mysql_setpermission \
 			mysql_secure_installation \
 			mysql_zap \
@@ -99,6 +102,7 @@ CLEANFILES =		@server_scripts@ \
 			mysql_tableinfo \
 			mysql_upgrade_shell \
 			mysqld_multi \
+			mysql_fix_privilege_tables.sql \
 			make_win_src_distribution_old
 
 # mysqlbug should be distributed built so that people can report build
@@ -130,7 +134,7 @@ mysql_fix_privilege_tables_sql.c: comp_sql.c mysql_fix_privilege_tables.sql
 	    $(top_srcdir)/scripts/mysql_fix_privilege_tables.sql $@
 
 
-SUFFIXES = .sh
+SUFFIXES = .sh .in
 
 .sh:
 	@RM@ -f $@ $@-t
@@ -185,6 +189,11 @@ SUFFIXES = .sh
 	@CHMOD@ +x $@-t
 	@MV@ $@-t $@
 
+.in:
+	@RM@ -f $@
+	@SED@ \
+	  -e 's!@''USERNAME_LENGTH''@!@USERNAME_LENGTH@!' \
+	$< > $@
 
 # Don't update the files from bitkeeper
 %::SCCS/s.%