diff --git a/_constraints b/_constraints
index d571c98..d2dc35b 100644
--- a/_constraints
+++ b/_constraints
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <constraints>
   <hardware>
-    <memory>
+    <physicalmemory>
       <size unit="M">2000</size>
-    </memory>
+    </physicalmemory>
   </hardware>
   <sandbox>kvm</sandbox>
+  <hostlabel exclude="true">SLOW_CPU</hostlabel>
 </constraints>
diff --git a/llvm.changes b/llvm.changes
index 8bd89d0..02ad140 100644
--- a/llvm.changes
+++ b/llvm.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Tue Jul 16 08:35:00 UTC 2013 - coolo@suse.com
+
+- do not build on slow or low memory workers
+
 -------------------------------------------------------------------
 Thu Jul  4 11:55:43 UTC 2013 - idonmez@suse.com