diff --git a/mozilla/browser/base/Makefile.in b/mozilla/browser/base/Makefile.in
index ee7a72ef35c..29a578e2420 100644
--- a/mozilla/browser/base/Makefile.in
+++ b/mozilla/browser/base/Makefile.in
@@ -62,10 +62,12 @@ endif
 
 ifndef MOZ_BRANDING_DIRECTORY
 libs locale::
-	$(INSTALL) $(srcdir)/content/browserconfig.properties $(DIST)/bin
+	$(SYSINSTALL) $(IFLAGS1) $(srcdir)/content/browserconfig.properties $(DIST)/bin
+	$(SYSINSTALL) $(IFLAGS1) $(srcdir)/content/old-homepage-default.properties $(DIST)/bin
 
 install::
-	$(SYSINSTALL) $(srcdir)/content/browserconfig.properties $(DESTDIR)$(mozappdir)
+	$(SYSINSTALL) $(IFLAGS1) $(srcdir)/content/browserconfig.properties $(DESTDIR)$(mozappdir)
+	$(SYSINSTALL) $(IFLAGS1) $(srcdir)/content/old-homepage-default.properties $(DESTDIR)$(mozappdir)
 endif
 
 ifneq (,$(filter windows mac cocoa, $(MOZ_WIDGET_TOOLKIT)))
diff --git a/mozilla/browser/base/content/old-homepage-default.properties b/mozilla/browser/base/content/old-homepage-default.properties
new file mode 100644
index 00000000000..e9e47c85a48
--- /dev/null
+++ b/mozilla/browser/base/content/old-homepage-default.properties
@@ -0,0 +1,2 @@
+# Do NOT localize or otherwise change these values
+browser.startup.homepage=http://www.mozilla.org/projects/bonecho/
diff --git a/mozilla/browser/base/content/safeMode.js b/mozilla/browser/base/content/safeMode.js
index 16d5b6b716c..7b2d2c7313f 100644
--- a/mozilla/browser/base/content/safeMode.js
+++ b/mozilla/browser/base/content/safeMode.js
@@ -47,6 +47,18 @@ function clearAllPrefs() {
   var prefService = Components.classes["@mozilla.org/preferences-service;1"]
                               .getService(Components.interfaces.nsIPrefService);
   prefService.resetUserPrefs();
+
+  // Remove the pref-overrides dir, if it exists
+  try {
+    var fileLocator = Components.classes["@mozilla.org/file/directory_service;1"]
+                                .getService(Components.interfaces.nsIProperties);
+    const NS_APP_PREFS_OVERRIDE_DIR = "PrefDOverride";
+    var prefOverridesDir = fileLocator.get(NS_APP_PREFS_OVERRIDE_DIR,
+                                           Components.interfaces.nsIFile);
+    prefOverridesDir.remove(true);
+  } catch (ex) {
+    Components.utils.reportError(ex);
+  }
 }
 
 function restoreDefaultBookmarks() {
diff --git a/mozilla/browser/components/dirprovider/nsBrowserDirectoryProvider.cpp b/mozilla/browser/components/dirprovider/nsBrowserDirectoryProvider.cpp
index f03f518fa92..d3a3a80014e 100755
--- a/mozilla/browser/components/dirprovider/nsBrowserDirectoryProvider.cpp
+++ b/mozilla/browser/components/dirprovider/nsBrowserDirectoryProvider.cpp
@@ -126,10 +126,19 @@ nsBrowserDirectoryProvider::GetFile(const char *aKey, PRBool *aPersist,
       nsCString path;
       rv = prefs->GetCharPref("browser.bookmarks.file", getter_Copies(path));
       if (NS_SUCCEEDED(rv)) {
-	NS_NewNativeLocalFile(path, PR_TRUE, (nsILocalFile**)(nsIFile**) getter_AddRefs(file));
+        NS_NewNativeLocalFile(path, PR_TRUE, (nsILocalFile**)(nsIFile**) getter_AddRefs(file));
       }
     }
   }
+  else if (!strcmp(aKey, NS_APP_EXISTING_PREF_OVERRIDE)) {
+    rv = NS_GetSpecialDirectory(NS_APP_DEFAULTS_50_DIR,
+                                getter_AddRefs(file));
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    file->AppendNative(NS_LITERAL_CSTRING("existing-profile-defaults.js"));
+    file.swap(*aResult);
+    return NS_OK;
+  }
   else if (!strcmp(aKey, NS_APP_MICROSUMMARY_DIR)) {
     rv = NS_GetSpecialDirectory(NS_XPCOM_CURRENT_PROCESS_DIR,
                                 getter_AddRefs(file));
diff --git a/mozilla/browser/components/dirprovider/nsBrowserDirectoryServiceDefs.h b/mozilla/browser/components/dirprovider/nsBrowserDirectoryServiceDefs.h
index d6999f7106c..ef045c38248 100644
--- a/mozilla/browser/components/dirprovider/nsBrowserDirectoryServiceDefs.h
+++ b/mozilla/browser/components/dirprovider/nsBrowserDirectoryServiceDefs.h
@@ -53,6 +53,7 @@
 // ----------------------------------------------------------------------------
 
 #define NS_APP_MICROSUMMARY_DIR                 "MicsumGens"
+#define NS_APP_EXISTING_PREF_OVERRIDE           "ExistingPrefOverride"
 
 // ----------------------------------------------------------------------------
 // Files and directories that exist on a per-profile basis.
diff --git a/mozilla/browser/components/nsBrowserContentHandler.js b/mozilla/browser/components/nsBrowserContentHandler.js
index b930f8135e6..bc0fdf622b8 100644
--- a/mozilla/browser/components/nsBrowserContentHandler.js
+++ b/mozilla/browser/components/nsBrowserContentHandler.js
@@ -137,6 +137,40 @@ function needHomepageOverride(prefb) {
   return OVERRIDE_NONE;
 }
 
+// Copies a pref override file into the user's profile pref-override folder,
+// and then tells the pref service to reload it's default prefs.
+function copyPrefOverride() {
+  try {
+    var fileLocator = Components.classes["@mozilla.org/file/directory_service;1"]
+                                .getService(Components.interfaces.nsIProperties);
+    const NS_APP_EXISTING_PREF_OVERRIDE = "ExistingPrefOverride";
+    var prefOverride = fileLocator.get(NS_APP_EXISTING_PREF_OVERRIDE,
+                                       Components.interfaces.nsIFile);
+    if (!prefOverride.exists())
+      return; // nothing to do
+
+    const NS_APP_PREFS_OVERRIDE_DIR     = "PrefDOverride";
+    var prefOverridesDir = fileLocator.get(NS_APP_PREFS_OVERRIDE_DIR,
+                                           Components.interfaces.nsIFile);
+
+    // Check for any existing pref overrides, and remove them if present
+    var existingPrefOverridesFile = prefOverridesDir.clone();
+    existingPrefOverridesFile.append(prefOverride.leafName);
+    if (existingPrefOverridesFile.exists())
+      existingPrefOverridesFile.remove(false);
+
+    prefOverride.copyTo(prefOverridesDir, null);
+
+    // Now that we've installed the new-profile pref override file,
+    // re-read the default prefs.
+    var prefSvcObs = Components.classes["@mozilla.org/preferences-service;1"]
+                               .getService(Components.interfaces.nsIObserver);
+    prefSvcObs.observe(null, "reload-default-prefs", null);
+  } catch (ex) {
+    Components.utils.reportError(ex);
+  }
+}
+
 function openWindow(parent, url, target, features, args) {
   var wwatch = Components.classes["@mozilla.org/embedcomp/window-watcher;1"]
                          .getService(nsIWindowWatcher);
@@ -444,9 +478,13 @@ var nsBrowserContentHandler = {
     try {
       switch (needHomepageOverride(prefb)) {
         case OVERRIDE_NEW_PROFILE:
+          // New profile
           overridePage = formatter.formatURLPref("startup.homepage_welcome_url");
           break;
         case OVERRIDE_NEW_MSTONE:
+          // Existing profile, new build
+          copyPrefOverride();
+
           // Check whether we have a session to restore. If we do, we assume
           // that this is an "update" session.
           var ss = Components.classes["@mozilla.org/browser/sessionstartup;1"]
diff --git a/mozilla/browser/installer/unix/packages-static b/mozilla/browser/installer/unix/packages-static
index a06f279df61..47adb84679c 100644
--- a/mozilla/browser/installer/unix/packages-static
+++ b/mozilla/browser/installer/unix/packages-static
@@ -16,8 +16,10 @@ bin/.autoreg
 bin/chrome/@AB_CD@.jar
 bin/chrome/@AB_CD@.manifest
 bin/defaults/pref/firefox-l10n.js
+bin/defaults/existing-profile-defaults.js
 ; If you add a new directory you must explicitly call addDirectory in ab-CD.jst
 bin/browserconfig.properties
+bin/old-homepage-default.properties
 bin/searchplugins/*
 bin/defaults/profile/bookmarks.html
 bin/defaults/profile/localstore.rdf
diff --git a/mozilla/browser/installer/windows/packages-static b/mozilla/browser/installer/windows/packages-static
index 55c966c2441..cf49b45afd7 100644
--- a/mozilla/browser/installer/windows/packages-static
+++ b/mozilla/browser/installer/windows/packages-static
@@ -16,7 +16,9 @@ bin/.autoreg
 bin\chrome\@AB_CD@.jar
 bin\chrome\@AB_CD@.manifest
 bin\defaults\pref\firefox-l10n.js
+bin\defaults\existing-profile-defaults.js
 bin\browserconfig.properties
+bin\old-homepage-default.properties
 bin\searchplugins\*
 bin\defaults\profile\bookmarks.html
 bin\defaults\profile\localstore.rdf
diff --git a/mozilla/browser/locales/Makefile.in b/mozilla/browser/locales/Makefile.in
index 1d4fca6ddf3..ba79cabf160 100644
--- a/mozilla/browser/locales/Makefile.in
+++ b/mozilla/browser/locales/Makefile.in
@@ -88,6 +88,17 @@ PREF_JS_EXPORTS = $(LOCALE_SRCDIR)/firefox-l10n.js
 
 include $(topsrcdir)/config/rules.mk
 
+libs::
+	@if test -f "$(LOCALE_SRCDIR)/existing-profile-defaults.js"; then \
+	  $(PERL) $(topsrcdir)/config/preprocessor.pl $(PREF_PPFLAGS) $(DEFINES) $(ACDEFINES) $(XULPPFLAGS) \
+	    $(LOCALE_SRCDIR)/existing-profile-defaults.js > $(FINAL_TARGET)/defaults/existing-profile-defaults.js; \
+	fi
+install::
+	@if test -f "$(LOCALE_SRCDIR)/existing-profile-defaults.js"; then \
+	  $(PERL) $(topsrcdir)/config/preprocessor.pl $(PREF_PPFLAGS) $(DEFINES) $(ACDEFINES) $(XULPPFLAGS) \
+	    $(LOCALE_SRCDIR)/existing-profile-defaults.js > $(DESTDIR)$(mozappdir)/defaults/existing-profile-defaults.js; \
+	fi
+
 ifeq ($(OS_ARCH),OS2)
 README_FILES = \
 	os2/README.txt \
diff --git a/mozilla/modules/libpref/src/nsPrefService.cpp b/mozilla/modules/libpref/src/nsPrefService.cpp
index e5ce946f707..490fdd9fd0a 100644
--- a/mozilla/modules/libpref/src/nsPrefService.cpp
+++ b/mozilla/modules/libpref/src/nsPrefService.cpp
@@ -199,6 +199,9 @@ NS_IMETHODIMP nsPrefService::Observe(nsISupports *aSubject, const char *aTopic,
       ResetUserPrefs();
       rv = ReadUserPrefs(nsnull);
     }
+  } else if (!nsCRT::strcmp(aTopic, "reload-default-prefs")) {
+    // Reload the default prefs from file.
+    pref_InitInitialObjects();
   }
   return rv;
 }
diff --git a/mozilla/other-licenses/branding/firefox/locales/Makefile.in b/mozilla/other-licenses/branding/firefox/locales/Makefile.in
index c46996f7f6d..42fa96fb78d 100755
--- a/mozilla/other-licenses/branding/firefox/locales/Makefile.in
+++ b/mozilla/other-licenses/branding/firefox/locales/Makefile.in
@@ -49,7 +49,11 @@ include $(topsrcdir)/config/rules.mk
 libs::
 	@$(PYTHON) $(topsrcdir)/config/Preprocessor.py $(DEFINES) $(ACDEFINES) \
 	  $(srcdir)/browserconfig.properties > $(FINAL_TARGET)/browserconfig.properties
+	@$(PERL) $(topsrcdir)/config/preprocessor.pl $(DEFINES) $(ACDEFINES) \
+	  $(srcdir)/old-homepage-default.properties > $(FINAL_TARGET)/old-homepage-default.properties
 
 install::
 	@$(PYTHON) $(topsrcdir)/config/Preprocessor.py $(DEFINES) $(ACDEFINES) \
 	  $(srcdir)/browserconfig.properties > $(DESTDIR)$(mozappdir)/browserconfig.properties
+	@$(PERL) $(topsrcdir)/config/preprocessor.pl $(DEFINES) $(ACDEFINES) \
+	  $(srcdir)/old-homepage-default.properties > $(DESTDIR)$(mozappdir)/old-homepage-default.properties
diff --git a/mozilla/other-licenses/branding/firefox/locales/browserconfig.properties b/mozilla/other-licenses/branding/firefox/locales/browserconfig.properties
index d11da93e5f4..fe11e018acf 100755
--- a/mozilla/other-licenses/branding/firefox/locales/browserconfig.properties
+++ b/mozilla/other-licenses/branding/firefox/locales/browserconfig.properties
@@ -1,3 +1,3 @@
 # Do NOT localize or otherwise change these values
-#expand browser.startup.homepage=http://__AB_CD__.start.mozilla.com/firefox?client=firefox-a&rls=__MOZ_DISTRIBUTION_ID_UNQUOTED__:__AB_CD__:official
-#expand browser.startup.homepage_reset=http://__AB_CD__.start.mozilla.com/firefox?client=firefox-a&rls=__MOZ_DISTRIBUTION_ID_UNQUOTED__:__AB_CD__:official
+#expand browser.startup.homepage=http://__AB_CD__.start2.mozilla.com/firefox?client=firefox-a&rls=__MOZ_DISTRIBUTION_ID_UNQUOTED__:__AB_CD__:official
+#expand browser.startup.homepage_reset=http://__AB_CD__.start2.mozilla.com/firefox?client=firefox-a&rls=__MOZ_DISTRIBUTION_ID_UNQUOTED__:__AB_CD__:official
diff --git a/mozilla/other-licenses/branding/firefox/locales/old-homepage-default.properties b/mozilla/other-licenses/branding/firefox/locales/old-homepage-default.properties
new file mode 100644
index 00000000000..43093e71227
--- /dev/null
+++ b/mozilla/other-licenses/branding/firefox/locales/old-homepage-default.properties
@@ -0,0 +1,2 @@
+# Do NOT localize or otherwise change these values
+#expand browser.startup.homepage=http://__AB_CD__.start.mozilla.com/firefox?client=firefox-a&rls=__MOZ_DISTRIBUTION_ID_UNQUOTED__:__AB_CD__:official
diff --git a/mozilla/toolkit/xre/nsXREDirProvider.cpp b/mozilla/toolkit/xre/nsXREDirProvider.cpp
index 5822c223a70..babb00837e5 100644
--- a/mozilla/toolkit/xre/nsXREDirProvider.cpp
+++ b/mozilla/toolkit/xre/nsXREDirProvider.cpp
@@ -95,6 +95,8 @@
 #define APP_REGISTRY_NAME "appreg"
 #endif
 
+#define PREF_OVERRIDE_DIRNAME "preferences"
+
 nsXREDirProvider* gDirServiceProvider = nsnull;
 
 nsXREDirProvider::nsXREDirProvider() :
@@ -349,6 +351,11 @@ nsXREDirProvider::GetFile(const char* aProperty, PRBool* aPersistent,
     else if (!strcmp(aProperty, NS_APP_DOWNLOADS_50_FILE)) {
       rv = file->AppendNative(NS_LITERAL_CSTRING("downloads.rdf"));
     }
+    else if (!strcmp(aProperty, NS_APP_PREFS_OVERRIDE_DIR)) {
+      rv = mProfileDir->Clone(getter_AddRefs(file));
+      rv |= file->AppendNative(NS_LITERAL_CSTRING(PREF_OVERRIDE_DIRNAME));
+      rv |= EnsureDirectoryExists(file);
+    }
     // XXXbsmedberg move these defines into application-specific providers.
     else if (!strcmp(aProperty, NS_APP_MAIL_50_DIR)) {
       rv = file->AppendNative(NS_LITERAL_CSTRING("Mail"));
@@ -555,22 +562,30 @@ nsXREDirProvider::GetFilesInternal(const char* aProperty,
   }
   else if (!strcmp(aProperty, NS_APP_PREFS_DEFAULTS_DIR_LIST)) {
     nsCOMArray<nsIFile> directories;
+    PRBool exists;
 
     if (mXULAppDir) {
       nsCOMPtr<nsIFile> file;
       mXULAppDir->Clone(getter_AddRefs(file));
       file->AppendNative(NS_LITERAL_CSTRING("defaults"));
       file->AppendNative(NS_LITERAL_CSTRING("preferences"));
-      PRBool exists;
       if (NS_SUCCEEDED(file->Exists(&exists)) && exists)
         directories.AppendObject(file);
     }
+    
+    if (mProfileDir) {
+      nsCOMPtr<nsIFile> overrideFile;
+      mProfileDir->Clone(getter_AddRefs(overrideFile));
+      overrideFile->AppendNative(NS_LITERAL_CSTRING(PREF_OVERRIDE_DIRNAME));
+      if (NS_SUCCEEDED(overrideFile->Exists(&exists)) && exists)
+        directories.AppendObject(overrideFile);
 
-    if (mProfileDir && !gSafeMode) {
-      static const char *const kAppendPrefDir[] = { "defaults", "preferences", nsnull };
+      if (!gSafeMode) {
+        static const char *const kAppendPrefDir[] = { "defaults", "preferences", nsnull };
 
-      LoadDirsIntoArray(profileFile, "ExtensionDirs",
-                        kAppendPrefDir, directories);
+        LoadDirsIntoArray(profileFile, "ExtensionDirs",
+                          kAppendPrefDir, directories);
+      }
     }
 
     rv = NS_NewArrayEnumerator(aResult, directories);
diff --git a/mozilla/xpcom/io/nsAppDirectoryServiceDefs.h b/mozilla/xpcom/io/nsAppDirectoryServiceDefs.h
index c056083ded8..8f5f06b4881 100755
--- a/mozilla/xpcom/io/nsAppDirectoryServiceDefs.h
+++ b/mozilla/xpcom/io/nsAppDirectoryServiceDefs.h
@@ -96,6 +96,7 @@
 #define NS_APP_PREFS_50_DIR                     "PrefD"         // Directory which contains user prefs       
 #define NS_APP_PREFS_50_FILE                    "PrefF"
 #define NS_APP_PREFS_DEFAULTS_DIR_LIST          "PrefDL"
+#define NS_APP_PREFS_OVERRIDE_DIR               "PrefDOverride" // Directory for per-profile defaults
         
 #define NS_APP_USER_PROFILE_50_DIR              "ProfD"
 #define NS_APP_USER_PROFILE_LOCAL_50_DIR        "ProfLD"