diff --git a/misc/dashboard/README b/misc/dashboard/README
index 2878daef0c9..b2bc3c2d379 100644
--- a/misc/dashboard/README
+++ b/misc/dashboard/README
@@ -6,11 +6,15 @@ The files in this directory constitute the continuous builder:
 
 godashboard/: An AppEngine that acts as a server
 builder.sh, buildcontrol.sh: used by the build slaves
+buildcron.sh: a build loop that can be run regularly via cron
 
 If you wish to run a Go builder, please email golang-dev@googlegroups.com
 
 
-Setting up a Go builder:
+To set up a Go builder automatically, run buildcron.sh
+(you might want to read it first to see what it does).
+
+To set up a Go builder by hand:
 
 * (Optional) create a new user 'gobuild'
 * Edit ~gobuild/.bash_profile and add the following:
diff --git a/misc/dashboard/buildcontrol.py b/misc/dashboard/buildcontrol.py
index b2f7728e973..91b684f7991 100644
--- a/misc/dashboard/buildcontrol.py
+++ b/misc/dashboard/buildcontrol.py
@@ -35,12 +35,12 @@ def main(args):
         buildport = int(os.environ['BUILDPORT'])
 
     try:
-        buildkey = file('%s/.gobuildkey' % os.environ['GOROOT'], 'r').read().strip()
+        buildkey = file('%s/.gobuildkey-%s' % (os.environ['HOME'], os.environ['BUILDER']), 'r').read().strip()
     except IOError:
         try:
             buildkey = file('%s/.gobuildkey' % os.environ['HOME'], 'r').read().strip()
         except IOError:
-            print >>sys.stderr, "Need key in $GOROOT/.gobuildkey or ~/.gobuildkey"
+            print >>sys.stderr, "Need key in ~/.gobuildkey-%s or ~/.gobuildkey" % os.environ['BUILDER']
             return
 
     if args[1] == 'init':
diff --git a/misc/dashboard/buildcron.sh b/misc/dashboard/buildcron.sh
new file mode 100644
index 00000000000..c344414a972
--- /dev/null
+++ b/misc/dashboard/buildcron.sh
@@ -0,0 +1,53 @@
+#!/bin/sh
+# Copyright 2010 The Go Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+# This script can be run to create a new builder and then
+# to keep it running via cron.  First, run it by hand until it
+# starts up without errors and can run the loop.  Then, once
+# you're confident that it works, add this to your crontab:
+#
+#   */5 * * * *  cd $HOME; path/to/buildcron.sh darwin 386 >/dev/null 2>/dev/null
+
+if [ $# != 2 ]; then
+	echo 'usage: buildcron.sh goos goarch' 1>&2
+	exit 2
+fi
+
+export GOOS=$1
+export GOARCH=$2
+
+# Check if we are already running.
+# First command must not be pipeline, to avoid seeing extra processes in ps.
+all=$(ps axwwu)
+pid=$(echo "$all" | grep "buildcron.sh $1 $2" | grep -v $$ | awk '{print $2}')
+if [ "$pid" != "" ]; then
+	exit 0
+fi
+
+export BUILDHOST=godashboard.appspot.com
+export BUILDER=${GOOS}-${GOARCH}
+export GOROOT=$HOME/go-$BUILDER/go
+export GOBIN=$HOME/go-$BUILDER/bin
+
+if [ ! -f ~/.gobuildkey-$BUILDER ]; then
+	echo "need gobuildkey for $BUILDER in ~/.gobuildkey-$BUILDER" 1>&2
+	exit 2
+fi
+
+if [ ! -d $GOROOT ]; then
+	mkdir -p $GOROOT
+	hg clone https://go.googlecode.com/hg/ $GOROOT
+fi
+mkdir -p $GOROOT/bin
+
+cd $GOROOT/..
+cp go/misc/dashboard/builder.sh go/misc/dashboard/buildcontrol.py .
+chmod a+x builder.sh buildcontrol.py
+cd go
+../buildcontrol.py next $BUILDER
+cd ..
+./builder.sh
+
+
diff --git a/misc/dashboard/builder.sh b/misc/dashboard/builder.sh
index d66ba08c351..0eaed8b344c 100644
--- a/misc/dashboard/builder.sh
+++ b/misc/dashboard/builder.sh
@@ -52,20 +52,28 @@ while true ; do
     mkdir -p candidate/bin || fatal "Cannot create candidate/bin"
     cd candidate/src || fatal "Cannot cd into candidate/src"
     echo "Building revision $rev"
-    ./all.bash > ../log 2>&1
+    ALL=all.bash
+    if [ -f all-$GOOS.bash ]; then
+        ALL=all-$GOOS.bash
+    elif [ -f all-$GOARCH.bash ]; then
+        ALL=all-$GOARCH.bash
+    fi
+    ./$ALL > ../log 2>&1
     if [ $? -ne 0 ] ; then
         echo "Recording failure for $rev"
         python ../../buildcontrol.py record $BUILDER $rev ../log || fatal "Cannot record result"
     else
         echo "Recording success for $rev"
         python ../../buildcontrol.py record $BUILDER $rev ok || fatal "Cannot record result"
-        echo "Running benchmarks"
-        cd pkg || fatal "failed to cd to pkg"
-        make bench > ../../benchmarks 2>&1
-        if [ $? -eq 0 ] ; then
-            python ../../../buildcontrol.py benchmarks $BUILDER $rev ../../benchmarks || fatal "Cannot record benchmarks"
+        if [ "$ALL" = "all.bash" ]; then
+            echo "Running benchmarks"
+            cd pkg || fatal "failed to cd to pkg"
+            make bench > ../../benchmarks 2>&1
+            if [ $? -eq 0 ] ; then
+                python ../../../buildcontrol.py benchmarks $BUILDER $rev ../../benchmarks || fatal "Cannot record benchmarks"
+            fi
+            cd .. || fatal "failed to cd out of pkg"
         fi
-        cd .. || fatal "failed to cd out of pkg"
     fi
     cd ../.. || fatal "Cannot cd up"
 done
diff --git a/misc/dashboard/godashboard/gobuild.py b/misc/dashboard/godashboard/gobuild.py
index 6cc9e5828da..32f95ca3d8c 100644
--- a/misc/dashboard/godashboard/gobuild.py
+++ b/misc/dashboard/godashboard/gobuild.py
@@ -62,13 +62,15 @@ class Log(db.Model):
 class Highwater(db.Model):
     commit = db.StringProperty()
 
+N = 30
+
 class MainPage(webapp.RequestHandler):
     def get(self):
         self.response.headers['Content-Type'] = 'text/html; charset=utf-8'
 
         q = Commit.all()
         q.order('-__key__')
-        results = q.fetch(30)
+        results = q.fetch(N)
 
         revs = [toRev(r) for r in results]
         builders = {}
@@ -104,17 +106,29 @@ class GetHighwater(webapp.RequestHandler):
 
         hw = Highwater.get_by_key_name('hw-%s' % builder)
         if hw is None:
-            # If no highwater has been recorded for this builder, we find the
-            # initial commit and return that.
+            # If no highwater has been recorded for this builder,
+            # we go back N+1 commits and return that.
             q = Commit.all()
-            q.filter('num =', 0)
-            commitzero = q.get()
+            q.order('-__key__')
+            c = q.fetch(N+1)[-1]
             self.response.set_status(200)
-            self.response.out.write(commitzero.node)
+            self.response.out.write(c.node)
             return
 
+        # if the proposed hw is too old, bump it forward
+        node = hw.commit
+        found = False
+        q = Commit.all()
+        q.order('-__key__')
+        recent = q.fetch(N+1)
+        for c in recent:
+            if c.node == node:
+                found = True
+                break
+        if not found:
+            node = recent[-1].node
         self.response.set_status(200)
-        self.response.out.write(hw.commit)
+        self.response.out.write(node)
 
 def auth(req):
     k = req.get('key')
@@ -134,6 +148,18 @@ class SetHighwater(webapp.RequestHandler):
         if c is None:
             self.response.set_status(404)
             return
+        
+        # if the proposed hw is too old, bump it forward
+        found = False
+        q = Commit.all()
+        q.order('-__key__')
+        recent = q.fetch(N+1)
+        for c in head:
+            if c.node == newhw:
+                found = True
+                break
+        if not found:
+            c = recent[-1]
 
         hw = Highwater(key_name = 'hw-%s' % builder)
         hw.commit = c.node