--- java/org/apache/tomcat/util/digester/Digester.java	(revision 1803027)
+++ java/org/apache/tomcat/util/digester/Digester.java	(working copy)
@@ -29,12 +29,17 @@ 
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 import java.util.PropertyPermission;
+import java.util.Set;
 
 import javax.xml.parsers.ParserConfigurationException;
 import javax.xml.parsers.SAXParser;
 import javax.xml.parsers.SAXParserFactory;
 
+import org.apache.catalina.Lifecycle;
+import org.apache.catalina.LifecycleEvent;
+import org.apache.catalina.LifecycleListener;
 import org.apache.juli.logging.Log;
 import org.apache.juli.logging.LogFactory;
 import org.apache.tomcat.util.ExceptionUtils;
@@ -308,6 +313,35 @@ 
     }
 
 
+    public static class SystemPropertyReplacementListener
+            implements LifecycleListener {
+        protected Log log = LogFactory.getLog(Digester.class);
+        protected StringManager sm = StringManager.getManager(Digester.class);
+        @Override
+        public void lifecycleEvent(LifecycleEvent event) {
+            if (propertySource != null && Lifecycle.BEFORE_INIT_EVENT.equals(event.getType())) {
+                IntrospectionUtils.PropertySource[] propertySources =
+                        new IntrospectionUtils.PropertySource[] { propertySource };
+                Properties properties = System.getProperties();
+                Set<String> names = properties.stringPropertyNames();
+                for (String name : names) {
+                    String value = System.getProperty(name);
+                    if (value != null) {
+                        try {
+                            String newValue = IntrospectionUtils.replaceProperties(value, null, propertySources);
+                            if (value != newValue) {
+                                System.setProperty(name, newValue);
+                            }
+                        } catch (Exception e) {
+                            log.warn(sm.getString("digester.failedToUpdateSystemProperty", name, value), e);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+
     // ------------------------------------------------------------- Properties
 
     /**
--- webapps/docs/config/systemprops.xml	(revision 1803027)
+++ webapps/docs/config/systemprops.xml	(working copy)
@@ -45,6 +45,10 @@ 
          Required to have a public constructor with no arguments.</p>
       <p>Use this to add a property source, that will be invoked when <code>${parameter}</code>
          denoted parameters are found in the XML files that Tomcat parses.</p>
+      <p>Property replacement from the specified property source on the JVM
+         system properties can also be done by adding the
+         <code>org.apache.tomcat.util.digester.Digester$SystemPropertyReplacementListener</code>
+         listener as a Server listener in the container.</p>
     </property>
   </properties>
 
--- java/org/apache/tomcat/util/digester/LocalStrings.properties	(revision 1803027)
+++ java/org/apache/tomcat/util/digester/LocalStrings.properties	(working copy)
@@ -15,3 +15,4 @@ 
 
 disgester.encodingInvalid=The encoding [{0}] is not recognised by the JRE and will be ignored
 digester.failedToUpdateAttributes=Attribute [{0}] failed to update and remains [{1}]
+digester.failedToUpdateSystemProperty=System property [{0}] failed to update and remains [{1}]