diff --git a/Makefile.am b/Makefile.am
index be2d34f8db8..35c5a51caf4 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -85,15 +85,14 @@ tags:
 	support-files/build-tags
 .PHONY:		init-db bin-dist
 
-# Test installation. Ports are configurable from the environment.
-
-MYSQL_TEST_MANAGER_PORT =	9305
-MYSQL_TEST_MASTER_PORT =	9306
-MYSQL_TEST_SLAVE_PORT =		9308
+# Target 'test' will run the regression test suite using the built server.
+#
+# If you are running in a shared environment, users can avoid clashing
+# port numbers by setting individual small numbers 1-100 to the
+# environment variable MTR_BUILD_THREAD. The script "mysql-test-run"
+# will then calculate the various port numbers it needs from this,
+# making sure each user use different ports.
 
 test:
 	cd mysql-test ; \
-	./mysql-test-run \
-		--manager-port=$(MYSQL_TEST_MANAGER_PORT) \
-		--master_port=$(MYSQL_TEST_MASTER_PORT) \
-		--slave_port=$(MYSQL_TEST_SLAVE_PORT)
+	./mysql-test-run
diff --git a/mysql-test/mysql-test-run.sh b/mysql-test/mysql-test-run.sh
index b760309bb5b..9a2c4345bae 100644
--- a/mysql-test/mysql-test-run.sh
+++ b/mysql-test/mysql-test-run.sh
@@ -201,6 +201,23 @@ MYSQL_MANAGER_PORT=9305 # needs to be out of the way of slaves
 MYSQL_MANAGER_PW_FILE=$MYSQL_TEST_DIR/var/tmp/manager.pwd
 MYSQL_MANAGER_LOG=$MYSQL_TEST_DIR/var/log/manager.log
 MYSQL_MANAGER_USER=root
+
+#
+# To make it easier for different devs to work on the same host,
+# an environment variable can be used to control all ports. A small
+# number is to be used, 0 - 16 or similar.
+#
+if [ -n "$MTR_BUILD_THREAD" ] ; then
+  MASTER_MYPORT=`expr $MTR_BUILD_THREAD '*' 40 + 8120`
+  SLAVE_MYPORT=`expr $MASTER_MYPORT + 16`
+  MYSQL_MANAGER_PORT=`expr $MASTER_MYPORT + 2`
+
+  echo "Using MTR_BUILD_THREAD   = $MTR_BUILD_THREAD"
+  echo "Using MASTER_MYPORT      = $MASTER_MYPORT"
+  echo "Using MYSQL_MANAGER_PORT = $MYSQL_MANAGER_PORT"
+  echo "Using SLAVE_MYPORT       = $SLAVE_MYPORT"
+fi
+
 NO_SLAVE=0
 USER_TEST=
 FAILED_CASES=