diff --git a/MANIFEST.in b/MANIFEST.in
index c4f12dc68a..092612cb21 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -2,7 +2,7 @@ recursive-include setuptools *.py *.exe *.xml *.tmpl
 recursive-include tests *.py
 recursive-include setuptools/tests *.html
 recursive-include docs *.py *.txt *.rst *.conf *.css *.css_t Makefile indexsidebar.html
-recursive-include setuptools/_vendor *.py *.txt
+recursive-include setuptools/_vendor *
 recursive-include pkg_resources *.py *.txt
 recursive-include pkg_resources/tests/data *
 recursive-include tools *
diff --git a/newsfragments/4480.bugfix.rst b/newsfragments/4480.bugfix.rst
new file mode 100644
index 0000000000..a43949fa7d
--- /dev/null
+++ b/newsfragments/4480.bugfix.rst
@@ -0,0 +1 @@
+Include all vendored files in the sdist.
\ No newline at end of file
diff --git a/setuptools/tests/test_setuptools.py b/setuptools/tests/test_setuptools.py
index 613a52d042..566af6980e 100644
--- a/setuptools/tests/test_setuptools.py
+++ b/setuptools/tests/test_setuptools.py
@@ -1,5 +1,6 @@
 """Tests for the 'setuptools' package"""
 
+import re
 import sys
 import os
 import distutils.core
@@ -315,3 +316,12 @@ def test_wheel_includes_cli_scripts(setuptools_wheel):
         contents = [f.replace(os.sep, '/') for f in zipfile.namelist()]
 
     assert any('cli-64.exe' in member for member in contents)
+
+
+def test_wheel_includes_vendored_metadata(setuptools_wheel):
+    with ZipFile(setuptools_wheel) as zipfile:
+        contents = [f.replace(os.sep, '/') for f in zipfile.namelist()]
+
+    assert any(
+        re.search(r'_vendor/.*\.dist-info/METADATA', member) for member in contents
+    )