diff --git a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/PDOMBugsTest.java b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/PDOMBugsTest.java
index 29d0a2dacdb..3e4f9230146 100644
--- a/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/PDOMBugsTest.java
+++ b/core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/pdom/tests/PDOMBugsTest.java
@@ -10,14 +10,20 @@
  *******************************************************************************/
 package org.eclipse.cdt.internal.pdom.tests;
 
+import java.io.File;
+
 import junit.framework.Test;
 
 import org.eclipse.cdt.core.dom.IPDOMManager;
+import org.eclipse.cdt.core.index.IIndexLocationConverter;
+import org.eclipse.cdt.core.index.ResourceContainerRelativeLocationConverter;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.testplugin.CProjectHelper;
 import org.eclipse.cdt.core.testplugin.util.BaseTestCase;
 import org.eclipse.cdt.internal.core.CCoreInternals;
+import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IWritableIndexFragment;
+import org.eclipse.cdt.internal.core.pdom.PDOM;
 import org.eclipse.cdt.internal.core.pdom.WritablePDOM;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.runtime.NullProgressMonitor;
@@ -59,4 +65,50 @@ public class PDOMBugsTest extends BaseTestCase {
 			pdom.releaseWriteLock(0);
 		}
 	}
+	
+	public void testProjectPDOMProperties() throws Exception {
+		IWritableIndexFragment pdom = (IWritableIndexFragment) CCoreInternals.getPDOMManager().getPDOM(cproject);
+		pdom.acquireReadLock();
+		try {
+			String id= pdom.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id);
+			
+			CCoreInternals.getPDOMManager().reindex(cproject);
+			
+			String id2= pdom.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id2);
+			assertEquals(id, id2);
+		} finally {
+			pdom.releaseReadLock();
+		}
+	}
+	
+	public void testProjectPDOMPropertiesOnExport() throws Exception {
+		File tmp= new File(System.getProperty("java.io.tmpdir")+"/temp"+System.currentTimeMillis()+".pdom");
+		IIndexLocationConverter cvr= new ResourceContainerRelativeLocationConverter(cproject.getProject());
+		CCoreInternals.getPDOMManager().exportProjectPDOM(cproject, tmp, cvr);
+		
+		IWritableIndexFragment pdom = new WritablePDOM(tmp, cvr);
+		pdom.acquireReadLock();
+		try {
+			String id= pdom.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id);
+			
+			String id2= ((PDOM)CCoreInternals.getPDOMManager().getPDOM(cproject)).getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id2);
+			assertFalse(id2.equals(id));
+			
+			CCoreInternals.getPDOMManager().reindex(cproject);
+			
+			String id3= pdom.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id3);
+			assertEquals(id,id3);
+			
+			String id4= ((PDOM)CCoreInternals.getPDOMManager().getPDOM(cproject)).getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+			assertNotNull(id4);
+			assertFalse(id4.equals(id));
+		} finally {
+			pdom.releaseReadLock();
+		}
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
index e5a5012e55a..3e09e95f43e 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/PDOMManager.java
@@ -42,6 +42,7 @@ import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.model.IElementChangedListener;
 import org.eclipse.cdt.core.model.ITranslationUnit;
 import org.eclipse.cdt.internal.core.CCoreInternals;
+import org.eclipse.cdt.internal.core.index.IIndexFragment;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.index.IWritableIndexManager;
 import org.eclipse.cdt.internal.core.index.IndexChangeEvent;
@@ -195,7 +196,11 @@ public class PDOMManager implements IPDOMManager, IWritableIndexManager, IListen
 					storeDatabaseName(rproject, dbName);
 				}
 			
+				boolean newPDOM= !dbFile.exists();
 				pdom = new WritablePDOM(dbFile, new PDOMProjectIndexLocationConverter(rproject));
+				if(newPDOM) {
+					writeProjectPDOMProperties(pdom, rproject);
+				}
 				pdom.addListener(this);
 			}
 			
@@ -873,6 +878,11 @@ public class PDOMManager implements IPDOMManager, IWritableIndexManager, IListen
 					PDOMFile file = (PDOMFile) i.next();
 					file.clear();
 				}
+				
+				// ensure fragment id has a sensible value, in case callee's do not
+				// overwrite their own values
+				String oldId= pdom.getProperty(IIndexFragment.PROPERTY_FRAGMENT_ID);
+				newPDOM.setProperty(IIndexFragment.PROPERTY_FRAGMENT_ID, "exported."+oldId); //$NON-NLS-1$
 			} finally {
 				newPDOM.releaseWriteLock();
 			}
@@ -914,6 +924,7 @@ public class PDOMManager implements IPDOMManager, IWritableIndexManager, IListen
 		try {
 			pdom.reloadFromFile(newFile);
 			storeDatabaseName(project.getProject(), newName);
+			writeProjectPDOMProperties(pdom, project.getProject());
 		}
 		finally {
 			pdom.releaseWriteLock();
@@ -926,4 +937,16 @@ public class PDOMManager implements IPDOMManager, IWritableIndexManager, IListen
 		operation.setOptions(options);
 		operation.run(monitor);
 	}
+	
+	/**
+	 * Write metadata appropriate for a project pdom
+	 * @param pdom the pdom to write to
+	 * @param project the project to write metadata about
+	 * @throws CoreException
+	 */
+	public static void writeProjectPDOMProperties(WritablePDOM pdom, IProject project) throws CoreException {
+		String DELIM = "\0"; //$NON-NLS-1$
+		String id= CCorePlugin.PLUGIN_ID + ".pdom.project." + DELIM + project.getName() + DELIM; //$NON-NLS-1$
+		pdom.setProperty(IIndexFragment.PROPERTY_FRAGMENT_ID, id);
+	}
 }
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
index 02821a8aa83..df115a190cb 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/pdom/indexer/PDOMRebuildTask.java
@@ -20,9 +20,12 @@ import org.eclipse.cdt.core.dom.IPDOMIndexerTask;
 import org.eclipse.cdt.core.dom.IPDOMManager;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.core.model.ITranslationUnit;
+import org.eclipse.cdt.internal.core.CCoreInternals;
 import org.eclipse.cdt.internal.core.index.IWritableIndex;
 import org.eclipse.cdt.internal.core.index.IWritableIndexManager;
 import org.eclipse.cdt.internal.core.pdom.IndexerProgress;
+import org.eclipse.cdt.internal.core.pdom.PDOMManager;
+import org.eclipse.cdt.internal.core.pdom.WritablePDOM;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.osgi.util.NLS;
@@ -69,6 +72,29 @@ public class PDOMRebuildTask implements IPDOMIndexerTask {
 		
 		if (fDelegate != null) {
 			fDelegate.run(monitor);
+			writeProjectProperties(project);
+		}
+	}
+	
+	/**
+	 * Writes project metadata to the pdom
+	 * @see PDOMManager#writeProjectPDOMProperties(WritablePDOM, org.eclipse.core.resources.IProject)
+	 * @param project the project to write project metadata about
+	 */
+	private void writeProjectProperties(ICProject project) {
+		try {
+			PDOMManager mgr= CCoreInternals.getPDOMManager();
+			WritablePDOM projectPDOM= (WritablePDOM) mgr.getPDOM(project);
+			projectPDOM.acquireWriteLock();
+			try {
+				PDOMManager.writeProjectPDOMProperties(projectPDOM, project.getProject());
+			} finally {
+				projectPDOM.releaseWriteLock();
+			}
+		} catch(CoreException ce) {
+			CCorePlugin.log(ce);
+		} catch(InterruptedException ie) {
+			// no-op
 		}
 	}