diff --git a/src/calibre/ebooks/metadata/opf2.py b/src/calibre/ebooks/metadata/opf2.py
index c603fcd41f..dd4e7e41b1 100644
--- a/src/calibre/ebooks/metadata/opf2.py
+++ b/src/calibre/ebooks/metadata/opf2.py
@@ -24,6 +24,23 @@ from calibre import prints, guess_type
 from calibre.utils.cleantext import clean_ascii_chars, clean_xml_chars
 from calibre.utils.config import tweaks
 
+pretty_print_opf = False
+
+class PrettyPrint(object):
+    def __enter__(self):
+        global pretty_print_opf
+        pretty_print_opf = True
+
+    def __exit__(self, *args):
+        global pretty_print_opf
+        pretty_print_opf = False
+pretty_print = PrettyPrint()
+
+def _pretty_print(root):
+    from calibre.ebooks.oeb.polish.pretty import pretty_opf, pretty_xml_tree
+    pretty_opf(root)
+    pretty_xml_tree(root)
+
 class Resource(object):  # {{{
     '''
     Represents a resource (usually a file on the filesystem or a URL pointing
@@ -1210,6 +1227,8 @@ class OPF(object):  # {{{
                 a['content'] = c
 
         self.write_user_metadata()
+        if pretty_print_opf:
+            _pretty_print(self.root)
         raw = etree.tostring(self.root, encoding=encoding, pretty_print=True)
         if not raw.lstrip().startswith('<?xml '):
             raw = '<?xml version="1.0"  encoding="%s"?>\n'%encoding.upper()+raw
@@ -1562,6 +1581,9 @@ def metadata_to_opf(mi, as_string=True, default_lang=None):
                 attrib={'type':'cover', 'title':_('Cover'), 'href':mi.cover})
         r.tail = '\n' +(' '*4)
         guide.append(r)
+    if pretty_print_opf:
+        _pretty_print(root)
+
     return etree.tostring(root, pretty_print=True, encoding='utf-8',
             xml_declaration=True) if as_string else root
 
diff --git a/src/calibre/gui2/actions/tweak_epub.py b/src/calibre/gui2/actions/tweak_epub.py
index 681ce04c4a..2f8eeb02d3 100755
--- a/src/calibre/gui2/actions/tweak_epub.py
+++ b/src/calibre/gui2/actions/tweak_epub.py
@@ -110,8 +110,8 @@ class TweakEpubAction(InterfaceAction):
                     _('The book must be in the %s formats to tweak.'
                         '\n\nFirst convert the book to one of these formats.') % (_(' or '.join(SUPPORTED))),
                     show=True)
+        from calibre.gui2.tweak_book import tprefs
         if len(tweakable_fmts) > 1:
-            from calibre.gui2.tweak_book import tprefs
             if tprefs['choose_tweak_fmt']:
                 d = Choose(sorted(tweakable_fmts, key=tprefs.defaults['tweak_fmt_order'].index), self.gui)
                 if d.exec_() != d.Accepted:
@@ -131,6 +131,12 @@ class TweakEpubAction(InterfaceAction):
                 ' library maintenance.') % fmt, show=True)
         tweak = 'ebook-tweak'
         self.gui.setCursor(Qt.BusyCursor)
+        if tprefs['update_metadata_from_calibre']:
+            from calibre.ebooks.metadata.opf2 import pretty_print
+            from calibre.ebooks.metadata.meta import set_metadata
+            mi = db.new_api.get_metadata(book_id)
+            with pretty_print, open(path, 'r+b') as f:
+                set_metadata(f, mi, stream_type=fmt.lower())
         try:
             self.gui.job_manager.launch_gui_app(tweak, kwargs=dict(args=[tweak, path]))
             time.sleep(2)
diff --git a/src/calibre/gui2/tweak_book/__init__.py b/src/calibre/gui2/tweak_book/__init__.py
index 72aec0661c..27c4549f1a 100644
--- a/src/calibre/gui2/tweak_book/__init__.py
+++ b/src/calibre/gui2/tweak_book/__init__.py
@@ -17,6 +17,7 @@ tprefs.defaults['editor_tab_stop_width'] = 2
 tprefs.defaults['preview_refresh_time'] = 2
 tprefs.defaults['choose_tweak_fmt'] = True
 tprefs.defaults['tweak_fmt_order'] = ['EPUB', 'AZW3']
+tprefs.defaults['update_metadata_from_calibre'] = True
 
 _current_container = None
 
diff --git a/src/calibre/gui2/tweak_book/preferences.py b/src/calibre/gui2/tweak_book/preferences.py
index 33607f6bfb..9ee4abaf05 100644
--- a/src/calibre/gui2/tweak_book/preferences.py
+++ b/src/calibre/gui2/tweak_book/preferences.py
@@ -178,6 +178,13 @@ class IntegrationSettings(BasicSettings):
         self.l = l = QFormLayout(self)
         self.setLayout(l)
 
+        um = self('update_metadata_from_calibre')
+        um.setText(_('Update metadata embedded in the book when opening'))
+        um.setToolTip('<p>' + _(
+            'When the file is opened, update the metadata embedded in the book file to the current metadata'
+            ' in the calibre library.'))
+        l.addRow(um)
+
         ask = self('choose_tweak_fmt')
         ask.setText(_('Ask which format to tweak if more than one format is available for the book'))
         l.addRow(ask)