diff --git a/doc/extdev/deprecated.rst b/doc/extdev/deprecated.rst
index f496dceae0..18b0e6d04e 100644
--- a/doc/extdev/deprecated.rst
+++ b/doc/extdev/deprecated.rst
@@ -22,6 +22,16 @@ The following is a list of deprecated interfaces.
      - (will be) Removed
      - Alternatives
 
+   * - ``sphinx.util.path_stabilize``
+     - 5.1
+     - 7.0
+     - ``sphinx.util.osutil.path_stabilize``
+
+   * - ``sphinx.util.get_matching_files``
+     - 5.1
+     - 7.0
+     - ``sphinx.util.matching.get_matching_files``
+
    * - ``sphinx.ext.napoleon.iterators``
      - 5.1
      - 7.0
diff --git a/doc/usage/configuration.rst b/doc/usage/configuration.rst
index 76f7642f79..d2ba22c26c 100644
--- a/doc/usage/configuration.rst
+++ b/doc/usage/configuration.rst
@@ -200,15 +200,14 @@ General configuration
 
 .. confval:: exclude_patterns
 
-   A list of glob-style patterns that should be excluded when looking for
-   source files. [1]_ They are matched against the source file names relative
+   A list of glob-style patterns [1]_ that should be excluded when looking for
+   source files. They are matched against the source file names relative
    to the source directory, using slashes as directory separators on all
    platforms.
 
    Example patterns:
 
-   - ``'library/xml.rst'`` -- ignores the ``library/xml.rst`` file (replaces
-     entry in :confval:`unused_docs`)
+   - ``'library/xml.rst'`` -- ignores the ``library/xml.rst`` file
    - ``'library/xml'`` -- ignores the ``library/xml`` directory
    - ``'library/xml*'`` -- ignores all files and directories starting with
      ``library/xml``
@@ -219,6 +218,26 @@ General configuration
 
    .. versionadded:: 1.0
 
+.. confval:: include_patterns
+
+   A list of glob-style patterns [1]_ that are used to find source files. They
+   are matched against the source file names relative to the source directory,
+   using slashes as directory separators on all platforms. The default is ``**``,
+   meaning that all files are recursively included from the source directory.
+
+   Example patterns:
+
+   - ``'**'`` -- all files in the source directory and subdirectories, recursively
+   - ``'library/xml'`` -- just the ``library/xml`` directory
+   - ``'library/xml*'`` -- all files and directories starting with ``library/xml``
+   - ``'**/doc'`` -- all ``doc`` directories (this might be useful if
+     documentation is co-located with source files)
+
+   :confval:`include_patterns` is also consulted when looking for static files
+   in :confval:`html_static_path` and :confval:`html_extra_path`.
+
+   .. versionadded:: 5.1
+
 .. confval:: templates_path
 
    A list of paths that contain extra templates (or templates that overwrite
diff --git a/sphinx/builders/html/__init__.py b/sphinx/builders/html/__init__.py
index c9832d1c59..cfd4b5c968 100644
--- a/sphinx/builders/html/__init__.py
+++ b/sphinx/builders/html/__init__.py
@@ -840,7 +840,8 @@ def onerror(filename: str, error: Exception) -> None:
             logger.warning(__('Failed to copy a file in html_static_file: %s: %r'),
                            filename, error)
 
-        excluded = Matcher(self.config.exclude_patterns + ["**/.*"])
+        excluded = Matcher(self.config.exclude_patterns + ["**/.*"],
+                           self.config.include_patterns)
         for entry in self.config.html_static_path:
             copy_asset(path.join(self.confdir, entry),
                        path.join(self.outdir, '_static'),
@@ -880,7 +881,7 @@ def copy_extra_files(self) -> None:
         """copy html_extra_path files."""
         try:
             with progress_message(__('copying extra files')):
-                excluded = Matcher(self.config.exclude_patterns)
+                excluded = Matcher(self.config.exclude_patterns, self.config.include_patterns)
                 for extra_path in self.config.html_extra_path:
                     entry = path.join(self.confdir, extra_path)
                     copy_asset(entry, self.outdir, excluded)
diff --git a/sphinx/config.py b/sphinx/config.py
index 318173f275..2fb41f066b 100644
--- a/sphinx/config.py
+++ b/sphinx/config.py
@@ -101,7 +101,8 @@ class Config:
         'root_doc': (lambda config: config.master_doc, 'env', []),
         'source_suffix': ({'.rst': 'restructuredtext'}, 'env', Any),
         'source_encoding': ('utf-8-sig', 'env', []),
-        'exclude_patterns': ([], 'env', []),
+        'exclude_patterns': ([], 'env', [str]),
+        'include_patterns': (["**"], 'env', [str]),
         'default_role': (None, 'env', [str]),
         'add_function_parentheses': (True, 'env', []),
         'add_module_names': (True, 'env', []),
diff --git a/sphinx/directives/other.py b/sphinx/directives/other.py
index 083fa088a7..38a332674e 100644
--- a/sphinx/directives/other.py
+++ b/sphinx/directives/other.py
@@ -84,7 +84,7 @@ def parse_content(self, toctree: addnodes.toctree) -> List[Node]:
         all_docnames.remove(self.env.docname)  # remove current document
 
         ret: List[Node] = []
-        excluded = Matcher(self.config.exclude_patterns)
+        excluded = Matcher(self.config.exclude_patterns, self.config.include_patterns)
         for entry in self.content:
             if not entry:
                 continue
diff --git a/sphinx/environment/__init__.py b/sphinx/environment/__init__.py
index 036aa3666d..df82c5a8a5 100644
--- a/sphinx/environment/__init__.py
+++ b/sphinx/environment/__init__.py
@@ -359,7 +359,7 @@ def find_files(self, config: Config, builder: "Builder") -> None:
             exclude_paths = (self.config.exclude_patterns +
                              self.config.templates_path +
                              builder.get_asset_paths())
-            self.project.discover(exclude_paths)
+            self.project.discover(exclude_paths, self.config.include_patterns)
 
             # Current implementation is applying translated messages in the reading
             # phase.Therefore, in order to apply the updated message catalog, it is
diff --git a/sphinx/environment/adapters/toctree.py b/sphinx/environment/adapters/toctree.py
index 631060e75a..a04c4da8fe 100644
--- a/sphinx/environment/adapters/toctree.py
+++ b/sphinx/environment/adapters/toctree.py
@@ -74,7 +74,7 @@ def resolve(self, docname: str, builder: "Builder", toctree: addnodes.toctree,
         # interactions between marking and pruning the tree (see bug #1046).
 
         toctree_ancestors = self.get_toctree_ancestors(docname)
-        excluded = Matcher(self.env.config.exclude_patterns)
+        excluded = Matcher(self.env.config.exclude_patterns, self.env.config.include_patterns)
 
         def _toctree_add_classes(node: Element, depth: int) -> None:
             """Add 'toctree-l%d' and 'current' classes to the toctree."""
diff --git a/sphinx/ext/autosummary/__init__.py b/sphinx/ext/autosummary/__init__.py
index 2b9055d3e8..eb5498e168 100644
--- a/sphinx/ext/autosummary/__init__.py
+++ b/sphinx/ext/autosummary/__init__.py
@@ -236,7 +236,7 @@ def run(self) -> List[Node]:
 
             tree_prefix = self.options['toctree'].strip()
             docnames = []
-            excluded = Matcher(self.config.exclude_patterns)
+            excluded = Matcher(self.config.exclude_patterns, self.config.include_patterns)
             filename_map = self.config.autosummary_filename_map
             for _name, _sig, _summary, real_name in items:
                 real_name = filename_map.get(real_name, real_name)
diff --git a/sphinx/project.py b/sphinx/project.py
index 1340558665..9e046faa76 100644
--- a/sphinx/project.py
+++ b/sphinx/project.py
@@ -2,12 +2,12 @@
 
 import os
 from glob import glob
-from typing import Dict, List, Optional, Set
+from typing import Dict, Iterable, Optional, Set
 
 from sphinx.locale import __
-from sphinx.util import get_matching_files, logging, path_stabilize
-from sphinx.util.matching import compile_matchers
-from sphinx.util.osutil import SEP, relpath
+from sphinx.util import logging
+from sphinx.util.matching import get_matching_files
+from sphinx.util.osutil import SEP, path_stabilize, relpath
 
 logger = logging.getLogger(__name__)
 EXCLUDE_PATHS = ['**/_sources', '.#*', '**/.#*', '*.lproj/**']
@@ -30,13 +30,17 @@ def restore(self, other: "Project") -> None:
         """Take over a result of last build."""
         self.docnames = other.docnames
 
-    def discover(self, exclude_paths: List[str] = []) -> Set[str]:
+    def discover(self, exclude_paths: Iterable[str] = (),
+                 include_paths: Iterable[str] = ("**",)) -> Set[str]:
         """Find all document files in the source directory and put them in
         :attr:`docnames`.
         """
         self.docnames = set()
-        excludes = compile_matchers(exclude_paths + EXCLUDE_PATHS)
-        for filename in get_matching_files(self.srcdir, excludes):  # type: ignore
+        for filename in get_matching_files(
+            self.srcdir,
+            [*exclude_paths] + EXCLUDE_PATHS,
+            include_paths,
+        ):
             docname = self.path2doc(filename)
             if docname:
                 if docname in self.docnames:
diff --git a/sphinx/util/__init__.py b/sphinx/util/__init__.py
index c80857a83b..0b0e1c952f 100644
--- a/sphinx/util/__init__.py
+++ b/sphinx/util/__init__.py
@@ -8,7 +8,7 @@
 import sys
 import tempfile
 import traceback
-import unicodedata
+import warnings
 from datetime import datetime
 from importlib import import_module
 from os import path
@@ -17,6 +17,7 @@
                     Optional, Pattern, Set, Tuple, Type, TypeVar)
 from urllib.parse import parse_qsl, quote_plus, urlencode, urlsplit, urlunsplit
 
+from sphinx.deprecation import RemovedInSphinx70Warning
 from sphinx.errors import ExtensionError, FiletypeNotFoundError, SphinxParallelError
 from sphinx.locale import __
 from sphinx.util import logging
@@ -50,16 +51,25 @@ def docname_join(basedocname: str, docname: str) -> str:
 
 def path_stabilize(filepath: str) -> str:
     "Normalize path separator and unicode string"
-    newpath = filepath.replace(os.path.sep, SEP)
-    return unicodedata.normalize('NFC', newpath)
+    warnings.warn("'sphinx.util.path_stabilize' is deprecated, use "
+                  "'sphinx.util.osutil.path_stabilize' instead.",
+                  RemovedInSphinx70Warning, stacklevel=2)
+    from sphinx.util import osutil
+
+    return osutil.path_stabilize(filepath)
 
 
 def get_matching_files(dirname: str,
-                       exclude_matchers: Tuple[PathMatcher, ...] = ()) -> Iterable[str]:  # NOQA
+                       exclude_matchers: Tuple[PathMatcher, ...] = (),
+                       include_matchers: Tuple[PathMatcher, ...] = ()) -> Iterable[str]:  # NOQA
     """Get all file names in a directory, recursively.
 
     Exclude files and dirs matching some matcher in *exclude_matchers*.
     """
+    warnings.warn("'sphinx.util.get_matching_files' is deprecated, use "
+                  "'sphinx.util.matching.get_matching_files' instead. Note that"
+                  "the types of the arguments have changed from callables to "
+                  "plain string glob patterns.", RemovedInSphinx70Warning, stacklevel=2)
     # dirname is a normalized absolute path.
     dirname = path.normpath(path.abspath(dirname))
 
diff --git a/sphinx/util/matching.py b/sphinx/util/matching.py
index 53a8933386..de4a776cfd 100644
--- a/sphinx/util/matching.py
+++ b/sphinx/util/matching.py
@@ -1,9 +1,10 @@
 """Pattern-matching utility functions for Sphinx."""
 
+import os.path
 import re
-from typing import Callable, Dict, Iterable, List, Match, Optional, Pattern
+from typing import Callable, Dict, Iterable, Iterator, List, Match, Optional, Pattern
 
-from sphinx.util.osutil import canon_path
+from sphinx.util.osutil import canon_path, path_stabilize
 
 
 def _translate_pattern(pat: str) -> str:
@@ -52,7 +53,7 @@ def _translate_pattern(pat: str) -> str:
     return res + '$'
 
 
-def compile_matchers(patterns: List[str]) -> List[Callable[[str], Optional[Match[str]]]]:
+def compile_matchers(patterns: Iterable[str]) -> List[Callable[[str], Optional[Match[str]]]]:
     return [re.compile(_translate_pattern(pat)).match for pat in patterns]
 
 
@@ -63,9 +64,10 @@ class Matcher:
           For example, "**/index.rst" matches with "index.rst"
     """
 
-    def __init__(self, patterns: List[str]) -> None:
-        expanded = [pat[3:] for pat in patterns if pat.startswith('**/')]
-        self.patterns = compile_matchers(patterns + expanded)
+    def __init__(self, exclude_patterns: Iterable[str],
+                 include_patterns: Iterable[str] = ()) -> None:
+        expanded = [pat[3:] for pat in exclude_patterns if pat.startswith('**/')]
+        self.patterns = compile_matchers(list(exclude_patterns) + expanded)
 
     def __call__(self, string: str) -> bool:
         return self.match(string)
@@ -99,3 +101,63 @@ def patfilter(names: Iterable[str], pat: str) -> List[str]:
         _pat_cache[pat] = re.compile(_translate_pattern(pat))
     match = _pat_cache[pat].match
     return list(filter(match, names))
+
+
+def get_matching_files(
+    dirname: str,
+    exclude_patterns: Iterable[str] = (),
+    include_patterns: Iterable[str] = ("**",)
+) -> Iterator[str]:
+    """Get all file names in a directory, recursively.
+
+    Filter file names by the glob-style include_patterns and exclude_patterns.
+    The default values include all files ("**") and exclude nothing ("").
+
+    Only files matching some pattern in *include_patterns* are included, and
+    exclusions from *exclude_patterns* take priority over inclusions.
+
+    """
+    # dirname is a normalized absolute path.
+    dirname = os.path.normpath(os.path.abspath(dirname))
+
+    exclude_matchers = compile_matchers(exclude_patterns)
+    include_matchers = compile_matchers(include_patterns)
+
+    for root, dirs, files in os.walk(dirname, followlinks=True):
+        relative_root = os.path.relpath(root, dirname)
+        if relative_root == ".":
+            relative_root = ""  # suppress dirname for files on the target dir
+
+        # Filter files
+        included_files = []
+        for entry in sorted(files):
+            entry = path_stabilize(os.path.join(relative_root, entry))
+            keep = False
+            for matcher in include_matchers:
+                if matcher(entry):
+                    keep = True
+                    break  # break the inner loop
+
+            for matcher in exclude_matchers:
+                if matcher(entry):
+                    keep = False
+                    break  # break the inner loop
+
+            if keep:
+                included_files.append(entry)
+
+        # Filter directories
+        filtered_dirs = []
+        for dir_name in sorted(dirs):
+            normalised = path_stabilize(os.path.join(relative_root, dir_name))
+            for matcher in exclude_matchers:
+                if matcher(normalised):
+                    break  # break the inner loop
+            else:
+                # if the loop didn't break
+                filtered_dirs.append(dir_name)
+
+        dirs[:] = filtered_dirs
+
+        # Yield filtered files
+        yield from included_files
diff --git a/sphinx/util/osutil.py b/sphinx/util/osutil.py
index 840655e425..d0ed42c8cd 100644
--- a/sphinx/util/osutil.py
+++ b/sphinx/util/osutil.py
@@ -6,6 +6,7 @@
 import re
 import shutil
 import sys
+import unicodedata
 from io import StringIO
 from os import path
 from typing import Any, Generator, Iterator, List, Optional, Type
@@ -34,6 +35,12 @@ def canon_path(nativepath: str) -> str:
     return nativepath.replace(path.sep, SEP)
 
 
+def path_stabilize(filepath: str) -> str:
+    "Normalize path separator and unicode string"
+    new_path = canon_path(filepath)
+    return unicodedata.normalize('NFC', new_path)
+
+
 def relative_uri(base: str, to: str) -> str:
     """Return a relative URL from ``base`` to ``to``."""
     if to.startswith(SEP):
diff --git a/tests/test_util_matching.py b/tests/test_util_matching.py
index ee1d3b2cb6..ecff0e2d83 100644
--- a/tests/test_util_matching.py
+++ b/tests/test_util_matching.py
@@ -1,5 +1,5 @@
 """Tests sphinx.util.matching functions."""
-from sphinx.util.matching import Matcher, compile_matchers
+from sphinx.util.matching import Matcher, compile_matchers, get_matching_files
 
 
 def test_compile_matchers():
@@ -80,3 +80,95 @@ def test_Matcher():
     assert not matcher('subdir/hello.py')
     assert matcher('world.py')
     assert matcher('subdir/world.py')
+
+
+def test_get_matching_files_all(rootdir):
+    files = get_matching_files(rootdir / "test-root")
+    assert sorted(files) == [
+        'Makefile', '_templates/contentssb.html', '_templates/customsb.html',
+        '_templates/layout.html', 'autodoc.txt', 'autodoc_target.py', 'bom.txt', 'conf.py',
+        'extapi.txt', 'extensions.txt', 'file_with_special_#_chars.xyz', 'footnote.txt',
+        'images.txt', 'img.foo.png', 'img.gif', 'img.pdf', 'img.png', 'includes.txt',
+        'index.txt', 'lists.txt', 'literal.inc', 'literal_orig.inc', 'markup.txt', 'math.txt',
+        'objects.txt', 'otherext.foo', 'parsermod.py', 'quotes.inc', 'rimg.png',
+        'special/api.h', 'special/code.py', 'subdir/excluded.txt', 'subdir/images.txt',
+        'subdir/img.png', 'subdir/include.inc', 'subdir/includes.txt', 'subdir/simg.png',
+        'svgimg.pdf', 'svgimg.svg', 'tabs.inc', 'test.inc', 'wrongenc.inc',
+    ]
+
+
+def test_get_matching_files_all_exclude_single(rootdir):
+    files = get_matching_files(rootdir / "test-root", ["**.html"])
+    assert sorted(files) == [
+        'Makefile', 'autodoc.txt', 'autodoc_target.py', 'bom.txt', 'conf.py',
+        'extapi.txt', 'extensions.txt', 'file_with_special_#_chars.xyz', 'footnote.txt',
+        'images.txt', 'img.foo.png', 'img.gif', 'img.pdf', 'img.png', 'includes.txt',
+        'index.txt', 'lists.txt', 'literal.inc', 'literal_orig.inc', 'markup.txt', 'math.txt',
+        'objects.txt', 'otherext.foo', 'parsermod.py', 'quotes.inc', 'rimg.png',
+        'special/api.h', 'special/code.py', 'subdir/excluded.txt', 'subdir/images.txt',
+        'subdir/img.png', 'subdir/include.inc', 'subdir/includes.txt', 'subdir/simg.png',
+        'svgimg.pdf', 'svgimg.svg', 'tabs.inc', 'test.inc', 'wrongenc.inc',
+    ]
+
+
+def test_get_matching_files_all_exclude_multiple(rootdir):
+    files = get_matching_files(rootdir / "test-root", ["**.html", "**.inc"])
+    assert sorted(files) == [
+        'Makefile', 'autodoc.txt', 'autodoc_target.py', 'bom.txt', 'conf.py',
+        'extapi.txt', 'extensions.txt', 'file_with_special_#_chars.xyz', 'footnote.txt',
+        'images.txt', 'img.foo.png', 'img.gif', 'img.pdf', 'img.png', 'includes.txt',
+        'index.txt', 'lists.txt', 'markup.txt', 'math.txt', 'objects.txt', 'otherext.foo',
+        'parsermod.py', 'rimg.png', 'special/api.h', 'special/code.py', 'subdir/excluded.txt',
+        'subdir/images.txt', 'subdir/img.png', 'subdir/includes.txt', 'subdir/simg.png',
+        'svgimg.pdf', 'svgimg.svg',
+    ]
+
+
+def test_get_matching_files_all_exclude_nonexistent(rootdir):
+    files = get_matching_files(rootdir / "test-root", ["halibut/**"])
+    assert sorted(files) == [
+        'Makefile', '_templates/contentssb.html', '_templates/customsb.html',
+        '_templates/layout.html', 'autodoc.txt', 'autodoc_target.py', 'bom.txt', 'conf.py',
+        'extapi.txt', 'extensions.txt', 'file_with_special_#_chars.xyz', 'footnote.txt',
+        'images.txt', 'img.foo.png', 'img.gif', 'img.pdf', 'img.png', 'includes.txt',
+        'index.txt', 'lists.txt', 'literal.inc', 'literal_orig.inc', 'markup.txt', 'math.txt',
+        'objects.txt', 'otherext.foo', 'parsermod.py', 'quotes.inc', 'rimg.png',
+        'special/api.h', 'special/code.py', 'subdir/excluded.txt', 'subdir/images.txt',
+        'subdir/img.png', 'subdir/include.inc', 'subdir/includes.txt', 'subdir/simg.png',
+        'svgimg.pdf', 'svgimg.svg', 'tabs.inc', 'test.inc', 'wrongenc.inc',
+    ]
+
+
+def test_get_matching_files_all_include_single(rootdir):
+    files = get_matching_files(rootdir / "test-root", [], ["subdir/**"])
+    assert sorted(files) == [
+        'subdir/excluded.txt', 'subdir/images.txt', 'subdir/img.png', 'subdir/include.inc',
+        'subdir/includes.txt', 'subdir/simg.png',
+    ]
+
+
+def test_get_matching_files_all_include_multiple(rootdir):
+    files = get_matching_files(rootdir / "test-root", [], ["special/**", "subdir/**"])
+    assert sorted(files) == [
+        'special/api.h', 'special/code.py', 'subdir/excluded.txt', 'subdir/images.txt',
+        'subdir/img.png', 'subdir/include.inc', 'subdir/includes.txt', 'subdir/simg.png',
+    ]
+
+
+def test_get_matching_files_all_include_nonexistent(rootdir):
+    files = get_matching_files(rootdir / "test-root", [], ["halibut/**"])
+    assert sorted(files) == []
+
+
+def test_get_matching_files_all_include_prefix(rootdir):
+    files = get_matching_files(rootdir / "test-root", [], ["autodoc*"])
+    assert sorted(files) == [
+        'autodoc.txt', 'autodoc_target.py',
+    ]
+
+
+def test_get_matching_files_all_include_question_mark(rootdir):
+    files = get_matching_files(rootdir / "test-root", [], ["img.???"])
+    assert sorted(files) == [
+        'img.gif', 'img.pdf', 'img.png',
+    ]