diff --git a/core/java/com/android/internal/backup/IBackupTransport.aidl b/core/java/com/android/internal/backup/IBackupTransport.aidl
index af06965ae1233..250bc9156c5c0 100644
--- a/core/java/com/android/internal/backup/IBackupTransport.aidl
+++ b/core/java/com/android/internal/backup/IBackupTransport.aidl
@@ -77,10 +77,15 @@ interface IBackupTransport {
      * @param data The data stream that resulted from invoking the application's
      *   BackupService.doBackup() method.  This may be a pipe rather than a file on
      *   persistent media, so it may not be seekable.
+     * @param wipeAllFirst When true, <i>all</i> backed-up data for the current device/account
+     *   will be erased prior to the storage of the data provided here.  The purpose of this
+     *   is to provide a guarantee that no stale data exists in the restore set when the
+     *   device begins providing backups.
      * @return false if errors occurred (the backup should be aborted and rescheduled),
      *   true if everything is OK so far (but {@link #finishBackup} must be called).
      */
-    boolean performBackup(in PackageInfo packageInfo, in ParcelFileDescriptor inFd);
+    boolean performBackup(in PackageInfo packageInfo, in ParcelFileDescriptor inFd,
+            boolean wipeAllFirst);
 
     /**
      * Erase the give application's data from the backup destination.  This clears
diff --git a/core/java/com/android/internal/backup/LocalTransport.java b/core/java/com/android/internal/backup/LocalTransport.java
index 2facce2ed1901..981ea82028a6f 100644
--- a/core/java/com/android/internal/backup/LocalTransport.java
+++ b/core/java/com/android/internal/backup/LocalTransport.java
@@ -56,12 +56,16 @@ public class LocalTransport extends IBackupTransport.Stub {
         return 0;
     }
 
-    public boolean performBackup(PackageInfo packageInfo, ParcelFileDescriptor data)
-            throws RemoteException {
+    public boolean performBackup(PackageInfo packageInfo, ParcelFileDescriptor data,
+            boolean wipeAllFirst) throws RemoteException {
         if (DEBUG) Log.v(TAG, "performBackup() pkg=" + packageInfo.packageName);
 
         File packageDir = new File(mDataDir, packageInfo.packageName);
         packageDir.mkdirs();
+        if (wipeAllFirst) {
+            if (DEBUG) Log.v(TAG, "wiping all data first");
+            deleteContents(mDataDir);
+        }
 
         // Each 'record' in the restore set is kept in its own file, named by
         // the record key.  Wind through the data file, extracting individual
@@ -111,6 +115,21 @@ public class LocalTransport extends IBackupTransport.Stub {
         }
     }
 
+    // Deletes the contents but not the given directory
+    private void deleteContents(File dirname) {
+        File[] contents = dirname.listFiles();
+        if (contents != null) {
+            for (File f : contents) {
+                if (f.isDirectory()) {
+                    // delete the directory's contents then fall through
+                    // and delete the directory itself.
+                    deleteContents(f);
+                }
+                f.delete();
+            }
+        }
+    }
+
     public boolean clearBackupData(PackageInfo packageInfo) {
         if (DEBUG) Log.v(TAG, "clearBackupData() pkg=" + packageInfo.packageName);
 
diff --git a/services/java/com/android/server/BackupManagerService.java b/services/java/com/android/server/BackupManagerService.java
index 41863276ed9cc..776de7eabb565 100644
--- a/services/java/com/android/server/BackupManagerService.java
+++ b/services/java/com/android/server/BackupManagerService.java
@@ -949,11 +949,11 @@ class BackupManagerService extends IBackupManager.Stub {
             }
         }
 
-        void processOneBackup(BackupRequest request, IBackupAgent agent, IBackupTransport transport) {
+        void processOneBackup(BackupRequest request, IBackupAgent agent,
+                IBackupTransport transport) {
             final String packageName = request.appInfo.packageName;
             if (DEBUG) Log.d(TAG, "processOneBackup doBackup() on " + packageName);
 
-            // !!! TODO: get the state file dir from the transport
             File savedStateName = new File(mStateDir, packageName);
             File backupDataName = new File(mDataDir, packageName + ".data");
             File newStateName = new File(mStateDir, packageName + ".new");
@@ -962,6 +962,12 @@ class BackupManagerService extends IBackupManager.Stub {
             ParcelFileDescriptor backupData = null;
             ParcelFileDescriptor newState = null;
 
+            // Usually we won't force a server-side init, except the first time
+            // we ever back up following enable of backup.  To keep the bookkeeping
+            // simple, we detect this here rather than maintain state throughout
+            // the backup manager.
+            boolean doInit = false;
+
             PackageInfo packInfo;
             try {
                 // Look up the package info & signatures.  This is first so that if it
@@ -971,6 +977,13 @@ class BackupManagerService extends IBackupManager.Stub {
                     // The metadata 'package' is synthetic
                     packInfo = new PackageInfo();
                     packInfo.packageName = packageName;
+
+                    // if there's no metadata backup state, this must be the
+                    // first time we've done one since enabling it.
+                    if (savedStateName.exists() == false) {
+                        if (DEBUG) Log.i(TAG, "First backup pass, issuing init");
+                        doInit = true;
+                    }
                 } else {
                     packInfo = mPackageManager.getPackageInfo(packageName,
                         PackageManager.GET_SIGNATURES);
@@ -1023,7 +1036,7 @@ class BackupManagerService extends IBackupManager.Stub {
                     // hold off on finishBackup() until the end, which implies holding off on
                     // renaming *all* the output state files (see below) until that happens.
 
-                    if (!transport.performBackup(packInfo, backupData) ||
+                    if (!transport.performBackup(packInfo, backupData, doInit) ||
                         !transport.finishBackup()) {
                         throw new Exception("Backup transport failed");
                     }