diff --git a/doc/config.rst b/doc/config.rst
index 891f080b5..9654e7856 100644
--- a/doc/config.rst
+++ b/doc/config.rst
@@ -870,6 +870,13 @@ that use Sphinx's HTMLWriter class.
 
    .. versionadded:: 0.6
 
+.. confval:: html_sourcelink_txt
+
+   If true, ``.txt`` is appended to source links (see
+   :confval:`html_show_sourcelink`).  Default is ``True``.
+
+   .. versionadded:: 1.5
+
 .. confval:: html_use_opensearch
 
    If nonempty, an `OpenSearch <http://www.opensearch.org/Home>`_ description file will be
diff --git a/sphinx/builders/html.py b/sphinx/builders/html.py
index 63ccdd66c..01a634bdd 100644
--- a/sphinx/builders/html.py
+++ b/sphinx/builders/html.py
@@ -402,15 +402,21 @@ class StandaloneHTMLBuilder(Builder):
         # title rendered as HTML
         title = self.env.longtitles.get(docname)
         title = title and self.render_partial(title)['title'] or ''
+
+        # Suffix for the document
+        source_suffix = path.splitext(self.env.doc2path(docname))[1]
+
         # the name for the copied source
-        sourcename = self.config.html_copy_source and docname + '.txt' or ''
+        if self.config.html_copy_source:
+            sourcename = docname + source_suffix
+            if self.config.html_sourcelink_txt and source_suffix != '.txt':
+                sourcename += '.txt'
+        else:
+            sourcename = ''
 
         # metadata for the document
         meta = self.env.metadata.get(docname)
 
-        # Suffix for the document
-        source_suffix = '.' + self.env.doc2path(docname).split('.')[-1]
-
         # local TOC and global TOC tree
         self_toc = self.env.get_toc_for(docname, self)
         toc = self.render_partial(self_toc)['fragment']
diff --git a/sphinx/config.py b/sphinx/config.py
index ef57334fe..cd05db45e 100644
--- a/sphinx/config.py
+++ b/sphinx/config.py
@@ -121,6 +121,7 @@ class Config(object):
         html_split_index = (False, 'html'),
         html_copy_source = (True, 'html'),
         html_show_sourcelink = (True, 'html'),
+        html_sourcelink_txt = (True, 'html'),
         html_use_opensearch = ('', 'html'),
         html_file_suffix = (None, 'html', string_classes),
         html_link_suffix = (None, 'html', string_classes),
diff --git a/tests/test_build_html.py b/tests/test_build_html.py
index 177fa71b5..df10c458c 100644
--- a/tests/test_build_html.py
+++ b/tests/test_build_html.py
@@ -319,7 +319,7 @@ HTML_XPATH = {
     ],
     'otherext.html': [
         (".//h1", "Generated section"),
-        (".//a[@href='_sources/otherext.txt']", ''),
+        (".//a[@href='_sources/otherext.foo.txt']", ''),
     ]
 }
 
@@ -987,3 +987,15 @@ def test_html_extra_path(app, status, warning):
     assert (app.outdir / 'rimg.png').exists()
     assert not (app.outdir / '_build/index.html').exists()
     assert (app.outdir / 'background.png').exists()
+
+
+@with_app(buildername='html', confoverrides={'html_sourcelink_txt': False})
+def test_html_sourcelink_txt(app, status, warning):
+    app.builder.build_all()
+    content_otherext = (app.outdir / 'otherext.html').text()
+    content_images = (app.outdir / 'images.html').text()
+
+    assert '<a href="_sources/otherext.foo"' in content_otherext
+    assert '<a href="_sources/images.txt"' in content_images
+    assert (app.outdir / '_sources' / 'otherext.foo').exists()
+    assert (app.outdir / '_sources' / 'images.txt').exists()