diff --git a/contrib/pg_upgrade/server.c b/contrib/pg_upgrade/server.c
new file mode 100644
index a9f9d85..49d4c8f
*** a/contrib/pg_upgrade/server.c
--- b/contrib/pg_upgrade/server.c
*************** start_postmaster(ClusterInfo *cluster)
*** 208,220 ****
  	 * maximum.  We assume all datfrozenxid and relfrozen values are less than
  	 * a gap of 2000000000 from the current xid counter, so autovacuum will
  	 * not touch them.
  	 */
  	snprintf(cmd, sizeof(cmd),
! 			 "\"%s/pg_ctl\" -w -l \"%s\" -D \"%s\" -o \"-p %d %s %s%s\" start",
  		  cluster->bindir, SERVER_LOG_FILE, cluster->pgconfig, cluster->port,
  			 (cluster->controldata.cat_ver >=
! 			  BINARY_UPGRADE_SERVER_FLAG_CAT_VER) ? "-b" :
! 			 "-c autovacuum=off -c autovacuum_freeze_max_age=2000000000",
  			 cluster->pgopts ? cluster->pgopts : "", socket_string);
  
  	/*
--- 208,225 ----
  	 * maximum.  We assume all datfrozenxid and relfrozen values are less than
  	 * a gap of 2000000000 from the current xid counter, so autovacuum will
  	 * not touch them.
+ 	 *
+ 	 *	synchronous_commit=off improves object creation speed, and we only
+ 	 *	modify the new cluster, so only use it there.  If there is a crash,
+ 	 *	the new cluster has to be recreated anyway.
  	 */
  	snprintf(cmd, sizeof(cmd),
! 			 "\"%s/pg_ctl\" -w -l \"%s\" -D \"%s\" -o \"-p %d%s%s%s%s\" start",
  		  cluster->bindir, SERVER_LOG_FILE, cluster->pgconfig, cluster->port,
  			 (cluster->controldata.cat_ver >=
! 			  BINARY_UPGRADE_SERVER_FLAG_CAT_VER) ? " -b" :
! 			 " -c autovacuum=off -c autovacuum_freeze_max_age=2000000000",
! 			 (cluster == &new_cluster) ? " -c synchronous_commit=off" : "",
  			 cluster->pgopts ? cluster->pgopts : "", socket_string);
  
  	/*