diff --git a/CHANGES b/CHANGES
index 84ef3b5f0..8fa478b69 100644
--- a/CHANGES
+++ b/CHANGES
@@ -43,6 +43,8 @@ Features added
 * PR#255: When generating latex references, also insert latex target/anchor
   for the ids defined on the node. Thanks to Olivier Heurtier.
 * PR#229: Allow registration of other translators. Thanks to Russell Sim.
+* Add app.set_translator() API to register or override a Docutils translator
+  class like :confval:`html_translator_class`.
 
 Bugs fixed
 ----------
diff --git a/doc/config.rst b/doc/config.rst
index 25135ef9a..5647cfdfc 100644
--- a/doc/config.rst
+++ b/doc/config.rst
@@ -706,6 +706,8 @@ that use Sphinx's HTMLWriter class.
    used to translate document trees to HTML.  Default is ``None`` (use the
    builtin translator).
 
+   .. seealso::  :meth:`~sphinx.application.Sphinx.set_translator`
+
 .. confval:: html_show_copyright
 
    If true, "(C) Copyright ..." is shown in the HTML footer. Default is
diff --git a/doc/extdev/appapi.rst b/doc/extdev/appapi.rst
index 5f1be739c..8df819439 100644
--- a/doc/extdev/appapi.rst
+++ b/doc/extdev/appapi.rst
@@ -82,13 +82,17 @@ package.
 
    Register an event called *name*.  This is needed to be able to emit it.
 
-.. method:: Sphinx.add_translator(name, translator_class)
+.. method:: Sphinx.set_translator(name, translator_class)
                
-   Register a Docutils translator class.  This is used to register a
-   custom output translator.  This allows extensions to define custom
-   nodes for the translator (see :meth:`add_node`).  If the name
-   clashes with an existing translator an
-   :exc:`sphinx.errors.ExtensionError` will be raised.
+   Register or override a Docutils translator class. This is used to register
+   a custom output translator or to replace a builtin translator.
+   This allows extensions to use custom translator and define custom
+   nodes for the translator (see :meth:`add_node`).
+
+   This is a API version of :confval:`html_translator_class` for all other
+   builders. Note that if :confval:`html_translator_class` is specified and
+   this API is called for html related builders, API overriding takes
+   precedence.
 
    .. versionadded:: 1.3
 
diff --git a/sphinx/application.py b/sphinx/application.py
index 99cf3d170..4a35bb181 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -99,8 +99,7 @@ class Sphinx(object):
         self.warningiserror = warningiserror
 
         self._events = events.copy()
-        self._translators = dict.fromkeys([
-            'html', 'latex', 'text', 'man', 'texinfo'])
+        self._translators = {}
 
         # say hello to the world
         self.info(bold('Running Sphinx v%s' % sphinx.__version__))
@@ -451,10 +450,8 @@ class Sphinx(object):
             raise ExtensionError('Event %r already present' % name)
         self._events[name] = ''
 
-    def add_translator(self, name, translator_class):
-        if name in self._translators:
-            raise ExtensionError('A Translator by the name '
-                                 '%s is already registered.' % name)
+    def set_translator(self, name, translator_class):
+        self.info(bold('A Translator for the %s builder is changed.' % name))
         self._translators[name] = translator_class
 
     def add_node(self, node, **kwds):
diff --git a/sphinx/builders/__init__.py b/sphinx/builders/__init__.py
index 44c76fafb..d8faf04a5 100644
--- a/sphinx/builders/__init__.py
+++ b/sphinx/builders/__init__.py
@@ -65,6 +65,9 @@ class Builder(object):
         # images that need to be copied over (source -> dest)
         self.images = {}
 
+        # load default translator class
+        self.translator_class = app._translators.get(self.name)
+
         self.init()
 
     # helper methods
diff --git a/sphinx/builders/html.py b/sphinx/builders/html.py
index a9e6a3680..926627a35 100644
--- a/sphinx/builders/html.py
+++ b/sphinx/builders/html.py
@@ -152,7 +152,9 @@ class StandaloneHTMLBuilder(Builder):
                                           self.config.trim_doctest_flags)
 
     def init_translator_class(self):
-        if self.config.html_translator_class:
+        if self.translator_class is not None:
+            pass
+        elif self.config.html_translator_class:
             self.translator_class = self.app.import_object(
                 self.config.html_translator_class,
                 'html_translator_class setting')
diff --git a/sphinx/builders/websupport.py b/sphinx/builders/websupport.py
index 6cf981023..7b0e6f724 100644
--- a/sphinx/builders/websupport.py
+++ b/sphinx/builders/websupport.py
@@ -46,7 +46,8 @@ class WebSupportBuilder(PickleHTMLBuilder):
         self.storage = storage
 
     def init_translator_class(self):
-        self.translator_class = WebSupportTranslator
+        if self.translator_class is None:
+            self.translator_class = WebSupportTranslator
 
     def prepare_writing(self, docnames):
         PickleHTMLBuilder.prepare_writing(self, docnames)
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index c40f3443b..d77c2c541 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -89,9 +89,11 @@ class LaTeXWriter(writers.Writer):
     def __init__(self, builder):
         writers.Writer.__init__(self)
         self.builder = builder
+        self.translator_class = (
+            self.builder.translator_class or LaTeXTranslator)
 
     def translate(self):
-        visitor = LaTeXTranslator(self.document, self.builder)
+        visitor = self.translator_class(self.document, self.builder)
         self.document.walkabout(visitor)
         self.output = visitor.astext()
 
diff --git a/sphinx/writers/manpage.py b/sphinx/writers/manpage.py
index 050f71d8b..8d49f807f 100644
--- a/sphinx/writers/manpage.py
+++ b/sphinx/writers/manpage.py
@@ -26,9 +26,11 @@ class ManualPageWriter(Writer):
     def __init__(self, builder):
         Writer.__init__(self)
         self.builder = builder
+        self.translator_class = (
+            self.builder.translator_class or ManualPageTranslator)
 
     def translate(self):
-        visitor = ManualPageTranslator(self.builder, self.document)
+        visitor = self.translator_class(self.builder, self.document)
         self.visitor = visitor
         self.document.walkabout(visitor)
         self.output = visitor.astext()
diff --git a/sphinx/writers/texinfo.py b/sphinx/writers/texinfo.py
index d8da901e4..a1051eb6a 100644
--- a/sphinx/writers/texinfo.py
+++ b/sphinx/writers/texinfo.py
@@ -120,9 +120,12 @@ class TexinfoWriter(writers.Writer):
     def __init__(self, builder):
         writers.Writer.__init__(self)
         self.builder = builder
+        self.translator_class = (
+            self.builder.translator_class or TexinfoTranslator)
 
     def translate(self):
-        self.visitor = visitor = TexinfoTranslator(self.document, self.builder)
+        self.visitor = visitor = self.translator_class(
+            self.document, self.builder)
         self.document.walkabout(visitor)
         visitor.finish()
         for attr in self.visitor_attributes:
diff --git a/sphinx/writers/text.py b/sphinx/writers/text.py
index 3f2edd145..b7d6c2869 100644
--- a/sphinx/writers/text.py
+++ b/sphinx/writers/text.py
@@ -140,9 +140,10 @@ class TextWriter(writers.Writer):
     def __init__(self, builder):
         writers.Writer.__init__(self)
         self.builder = builder
+        self.translator_class = self.builder.translator_class or TextTranslator
 
     def translate(self):
-        visitor = TextTranslator(self.document, self.builder)
+        visitor = self.translator_class(self.document, self.builder)
         self.document.walkabout(visitor)
         self.output = visitor.body
 
diff --git a/sphinx/writers/xml.py b/sphinx/writers/xml.py
index cfae484ef..179a9ab4f 100644
--- a/sphinx/writers/xml.py
+++ b/sphinx/writers/xml.py
@@ -18,6 +18,8 @@ class XMLWriter(BaseXMLWriter):
     def __init__(self, builder):
         BaseXMLWriter.__init__(self)
         self.builder = builder
+        if self.builder.translator_class:
+            self.translator_class = self.builder.translator_class
 
     def translate(self, *args, **kwargs):
         self.document.settings.newlines = \
diff --git a/tests/roots/test-api-set-translator/conf.py b/tests/roots/test-api-set-translator/conf.py
new file mode 100644
index 000000000..5b172f0e1
--- /dev/null
+++ b/tests/roots/test-api-set-translator/conf.py
@@ -0,0 +1,82 @@
+# -*- coding: utf-8 -*-
+
+import os
+import sys
+
+from sphinx.writers.html import HTMLTranslator
+from sphinx.writers.latex import LaTeXTranslator
+from sphinx.writers.manpage import ManualPageTranslator
+from sphinx.writers.texinfo import TexinfoTranslator
+from sphinx.writers.text import TextTranslator
+from sphinx.writers.websupport import WebSupportTranslator
+from docutils.writers.docutils_xml import XMLTranslator
+
+
+sys.path.insert(0, os.path.abspath('.'))
+
+
+project = 'test'
+master_doc = 'index'
+
+
+class ConfHTMLTranslator(HTMLTranslator):
+    pass
+
+
+class ConfDirHTMLTranslator(HTMLTranslator):
+    pass
+
+
+class ConfSingleHTMLTranslator(HTMLTranslator):
+    pass
+
+
+class ConfPickleTranslator(HTMLTranslator):
+    pass
+
+
+class ConfJsonTranslator(HTMLTranslator):
+    pass
+
+
+class ConfLaTeXTranslator(LaTeXTranslator):
+    pass
+
+
+class ConfManualPageTranslator(ManualPageTranslator):
+    pass
+
+
+class ConfTexinfoTranslator(TexinfoTranslator):
+    pass
+
+
+class ConfTextTranslator(TextTranslator):
+    pass
+
+
+class ConfWebSupportTranslator(WebSupportTranslator):
+    pass
+
+
+class ConfXMLTranslator(XMLTranslator):
+    pass
+
+
+class ConfPseudoXMLTranslator(XMLTranslator):
+    pass
+
+
+def setup(app):
+    app.set_translator('html', ConfHTMLTranslator)
+    app.set_translator('dirhtml', ConfDirHTMLTranslator)
+    app.set_translator('singlehtml', ConfSingleHTMLTranslator)
+    app.set_translator('pickle', ConfPickleTranslator)
+    app.set_translator('json', ConfJsonTranslator)
+    app.set_translator('latex', ConfLaTeXTranslator)
+    app.set_translator('man', ConfManualPageTranslator)
+    app.set_translator('texinfo', ConfTexinfoTranslator)
+    app.set_translator('text', ConfTextTranslator)
+    app.set_translator('websupport', ConfWebSupportTranslator)
+    app.set_translator('xml', ConfXMLTranslator)
+    app.set_translator('pseudoxml', ConfPseudoXMLTranslator)
diff --git a/tests/roots/test-api-set-translator/index.rst b/tests/roots/test-api-set-translator/index.rst
new file mode 100644
index 000000000..101bd39af
--- /dev/null
+++ b/tests/roots/test-api-set-translator/index.rst
@@ -0,0 +1,3 @@
+=======================
+Test API set_translator
+=======================
\ No newline at end of file
diff --git a/tests/roots/test-api-set-translator/nonext/conf.py b/tests/roots/test-api-set-translator/nonext/conf.py
new file mode 100644
index 000000000..a07b3c27c
--- /dev/null
+++ b/tests/roots/test-api-set-translator/nonext/conf.py
@@ -0,0 +1,9 @@
+# -*- coding: utf-8 -*-
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.abspath('.')))
+
+project = 'test'
+master_doc = 'index'
diff --git a/tests/roots/test-api-set-translator/translator.py b/tests/roots/test-api-set-translator/translator.py
new file mode 100644
index 000000000..d5c23d394
--- /dev/null
+++ b/tests/roots/test-api-set-translator/translator.py
@@ -0,0 +1,6 @@
+# -*- coding: utf-8 -*-
+
+from sphinx.writers.html import HTMLTranslator
+
+class ExtHTMLTranslator(HTMLTranslator):
+    pass
diff --git a/tests/test_api_translator.py b/tests/test_api_translator.py
new file mode 100644
index 000000000..1606e645d
--- /dev/null
+++ b/tests/test_api_translator.py
@@ -0,0 +1,185 @@
+# -*- coding: utf-8 -*-
+"""
+    test_api_translator
+    ~~~~~~~~~~~~~~~~~~~
+
+    Test the Sphinx API for translator.
+
+    :copyright: Copyright 2007-2014 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+from util import with_app, test_roots
+
+
+@with_app(
+    buildername='html',
+    srcdir=(test_roots / 'test-api-set-translator'),
+    confdir=(test_roots / 'test-api-set-translator' / 'nonext'),
+)
+def test_html_translator(app):
+    # no set_translator(), no html_translator_class
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'SmartyPantsHTMLTranslator'
+
+
+@with_app(
+    buildername='html',
+    srcdir=(test_roots / 'test-api-set-translator'),
+    confdir=(test_roots / 'test-api-set-translator' / 'nonext'),
+    confoverrides={
+        'html_translator_class': 'translator.ExtHTMLTranslator'},
+)
+def test_html_with_html_translator_class(app):
+    # no set_translator(), but html_translator_class
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ExtHTMLTranslator'
+
+
+@with_app(
+    buildername='html',
+    srcdir=(test_roots / 'test-api-set-translator'),
+    confdir=(test_roots / 'test-api-set-translator' / 'nonext'),
+    confoverrides={'html_use_smartypants': False},
+)
+def test_html_with_smartypants(app):
+    # no set_translator(), html_use_smartypants=False
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'HTMLTranslator'
+
+
+@with_app(
+    buildername='html',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_html_(app):
+    # use set_translator(), no html_translator_class
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfHTMLTranslator'
+
+
+@with_app(
+    buildername='html',
+    srcdir=(test_roots / 'test-api-set-translator'),
+    confoverrides={'html_translator_class': 'ext.ExtHTMLTranslator'},
+)
+def test_html_with_set_translator_for_html_and_html_translator_class(app):
+    # use set_translator() and html_translator_class.
+    # set_translator() is given priority over html_translator_clas.
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfHTMLTranslator'
+
+
+@with_app(
+    buildername='dirhtml',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_dirhtml_set_translator_for_dirhtml(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfDirHTMLTranslator'
+
+
+@with_app(
+    buildername='singlehtml',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_singlehtml_set_translator_for_singlehtml(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfSingleHTMLTranslator'
+
+
+@with_app(
+    buildername='pickle',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_pickle_set_translator_for_pickle(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfPickleTranslator'
+
+
+@with_app(
+    buildername='json',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_json_set_translator_for_json(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfJsonTranslator'
+
+
+@with_app(
+    buildername='latex',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_latex(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfLaTeXTranslator'
+
+
+@with_app(
+    buildername='man',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_man(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfManualPageTranslator'
+
+
+@with_app(
+    buildername='texinfo',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_texinfo(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfTexinfoTranslator'
+
+
+@with_app(
+    buildername='text',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_text(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfTextTranslator'
+
+
+@with_app(
+    buildername='websupport',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_websupport(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfWebSupportTranslator'
+
+
+@with_app(
+    buildername='xml',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_xml(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfXMLTranslator'
+
+
+@with_app(
+    buildername='pseudoxml',
+    srcdir=(test_roots / 'test-api-set-translator'),
+)
+def test_html_with_set_translator_for_pseudoxml(app):
+    translator_class = app.builder.translator_class
+    assert translator_class
+    assert translator_class.__name__ == 'ConfPseudoXMLTranslator'