diff --git a/docs/packaging.md b/docs/packaging.md
index 6d063ed..af822b0 100755
--- a/docs/packaging.md
+++ b/docs/packaging.md
@@ -91,7 +91,7 @@
 | classifiers |  A list of strings describing the categories for the package. For valid classifiers see https://pypi.org/classifiers   | List of strings | optional | [] |
 | console_scripts |  Deprecated console_script entry points, e.g. <code>{'main': 'examples.wheel.main:main'}</code>.<br><br>Deprecated: prefer the <code>entry_points</code> attribute, which supports <code>console_scripts</code> as well as other entry points.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> String</a> | optional | {} |
 | deps |  Targets to be included in the distribution.<br><br>The targets to package are usually <code>py_library</code> rules or filesets (for packaging data files).<br><br>Note it's usually better to package <code>py_library</code> targets and use <code>entry_points</code> attribute to specify <code>console_scripts</code> than to package <code>py_binary</code> rules. <code>py_binary</code> targets would wrap a executable script that tries to locate <code>.runfiles</code> directory which is not packaged in the wheel.   | <a href="https://bazel.build/docs/build-ref.html#labels">List of labels</a> | optional | [] |
-| description_file |  A file containing text describing the package in a single line.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
+| description_file |  A file containing text describing the package.   | <a href="https://bazel.build/docs/build-ref.html#labels">Label</a> | optional | None |
 | distribution |  Name of the distribution.<br><br>This should match the project name onm PyPI. It's also the name that is used to refer to the package in other packages' dependencies.   | String | required |  |
 | entry_points |  entry_points, e.g. <code>{'console_scripts': ['main = examples.wheel.main:main']}</code>.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: String -> List of strings</a> | optional | {} |
 | extra_distinfo_files |  Extra files to add to distinfo directory in the archive.   | <a href="https://bazel.build/docs/skylark/lib/dict.html">Dictionary: Label -> String</a> | optional | {} |
@@ -99,9 +99,9 @@
 | homepage |  A string specifying the URL for the package homepage.   | String | optional | "" |
 | license |  A string specifying the license of the package.   | String | optional | "" |
 | platform |  Supported platform. Use 'any' for pure-Python wheel.<br><br>If you have included platform-specific data, such as a .pyd or .so extension module, you will need to specify the platform in standard pip format. If you support multiple platforms, you can define platform constraints, then use a select() to specify the appropriate specifier, eg:<br><br><code> platform = select({     "//platforms:windows_x86_64": "win_amd64",     "//platforms:macos_x86_64": "macosx_10_7_x86_64",     "//platforms:linux_x86_64": "manylinux2014_x86_64", }) </code>   | String | optional | "any" |
-| python_requires |  A string specifying what other distributions need to be installed when this one is. See the section on [Declaring required dependency](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#declaring-dependencies) for details and examples of the format of this argument.   | String | optional | "" |
+| python_requires |  Python versions required by this distribution, e.g. '&gt;=3.5,&lt;3.7'   | String | optional | "" |
 | python_tag |  Supported Python version(s), eg <code>py3</code>, <code>cp35.cp36</code>, etc   | String | optional | "py3" |
-| requires |  List of requirements for this package   | List of strings | optional | [] |
+| requires |  List of requirements for this package. See the section on [Declaring required dependency](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#declaring-dependencies) for details and examples of the format of this argument.   | List of strings | optional | [] |
 | stamp |  Whether to encode build information into the wheel. Possible values:<br><br>- <code>stamp = 1</code>: Always stamp the build information into the wheel, even in [--nostamp](https://docs.bazel.build/versions/main/user-manual.html#flag--stamp) builds. This setting should be avoided, since it potentially kills remote caching for the target and any downstream actions that depend on it.<br><br>- <code>stamp = 0</code>: Always replace build information by constant values. This gives good build result caching.<br><br>- <code>stamp = -1</code>: Embedding of build information is controlled by the [--[no]stamp](https://docs.bazel.build/versions/main/user-manual.html#flag--stamp) flag.<br><br>Stamped targets are not rebuilt unless their dependencies change.   | Integer | optional | -1 |
 | strip_path_prefixes |  path prefixes to strip from files added to the generated package   | List of strings | optional | [] |
 | version |  Version number of the package. Note that this attribute supports stamp format strings (eg. <code>1.2.3-{BUILD_TIMESTAMP}</code>) as well as 'make variables' (e.g. <code>1.2.3-$(VERSION)</code>).   | String | required |  |
diff --git a/examples/wheel/wheel_test.py b/examples/wheel/wheel_test.py
index 0e495eb..cbca092 100644
--- a/examples/wheel/wheel_test.py
+++ b/examples/wheel/wheel_test.py
@@ -94,40 +94,11 @@
             entry_point_contents = zf.read(
                 "example_customized-0.0.1.dist-info/entry_points.txt"
             )
-            # The entries are guaranteed to be sorted.
-            if platform.system() == "Windows":
-                self.assertEqual(
-                    record_contents,
-                    b"""\
-example_customized-0.0.1.dist-info/METADATA,sha256=pzE96o3Sp63TDzxAZgl0F42EFevm8x15vpDLqDVp_EQ,378
-example_customized-0.0.1.dist-info/NOTICE,sha256=Xpdw-FXET1IRgZ_wTkx1YQfo1-alET0FVf6V1LXO4js,76
-example_customized-0.0.1.dist-info/README,sha256=WmOFwZ3Jga1bHG3JiGRsUheb4UbLffUxyTdHczS27-o,40
-example_customized-0.0.1.dist-info/RECORD,,
-example_customized-0.0.1.dist-info/WHEEL,sha256=sobxWSyDDkdg_rinUth-jxhXHqoNqlmNMJY3aTZn2Us,91
-example_customized-0.0.1.dist-info/entry_points.txt,sha256=pqzpbQ8MMorrJ3Jp0ntmpZcuvfByyqzMXXi2UujuXD0,137
-examples/wheel/lib/data.txt,sha256=9vJKEdfLu8bZRArKLroPZJh1XKkK3qFMXiM79MBL2Sg,12
-examples/wheel/lib/module_with_data.py,sha256=8s0Khhcqz3yVsBKv2IB5u4l4TMKh7-c_V6p65WVHPms,637
-examples/wheel/lib/simple_module.py,sha256=z2hwciab_XPNIBNH8B1Q5fYgnJvQTeYf0ZQJpY8yLLY,637
-examples/wheel/main.py,sha256=sgg5iWN_9inYBjm6_Zw27hYdmo-l24fA-2rfphT-IlY,909
-""",
-                )
-            else:
-                # TODO: The non-ascii characters in the METADATA file are interpreted differently on the
-                # ubuntu16_rbe hosts in comparison to other unix platforms. This should not be the case
-                # and the code should be updated to account for this.
-                rbe_expected_contents = b"""\
-example_customized-0.0.1.dist-info/METADATA,sha256=pzE96o3Sp63TDzxAZgl0F42EFevm8x15vpDLqDVp_EQ,378
-example_customized-0.0.1.dist-info/NOTICE,sha256=Xpdw-FXET1IRgZ_wTkx1YQfo1-alET0FVf6V1LXO4js,76
-example_customized-0.0.1.dist-info/README,sha256=WmOFwZ3Jga1bHG3JiGRsUheb4UbLffUxyTdHczS27-o,40
-example_customized-0.0.1.dist-info/RECORD,,
-example_customized-0.0.1.dist-info/WHEEL,sha256=sobxWSyDDkdg_rinUth-jxhXHqoNqlmNMJY3aTZn2Us,91
-example_customized-0.0.1.dist-info/entry_points.txt,sha256=pqzpbQ8MMorrJ3Jp0ntmpZcuvfByyqzMXXi2UujuXD0,137
-examples/wheel/lib/data.txt,sha256=9vJKEdfLu8bZRArKLroPZJh1XKkK3qFMXiM79MBL2Sg,12
-examples/wheel/lib/module_with_data.py,sha256=8s0Khhcqz3yVsBKv2IB5u4l4TMKh7-c_V6p65WVHPms,637
-examples/wheel/lib/simple_module.py,sha256=z2hwciab_XPNIBNH8B1Q5fYgnJvQTeYf0ZQJpY8yLLY,637
-examples/wheel/main.py,sha256=sgg5iWN_9inYBjm6_Zw27hYdmo-l24fA-2rfphT-IlY,909
-"""
-                unix_expected_contents = b"""\
+
+            self.assertEqual(
+                record_contents,
+                # The entries are guaranteed to be sorted.
+                b"""\
 example_customized-0.0.1.dist-info/METADATA,sha256=TeeEmokHE2NWjkaMcVJuSAq4_AXUoIad2-SLuquRmbg,372
 example_customized-0.0.1.dist-info/NOTICE,sha256=Xpdw-FXET1IRgZ_wTkx1YQfo1-alET0FVf6V1LXO4js,76
 example_customized-0.0.1.dist-info/README,sha256=WmOFwZ3Jga1bHG3JiGRsUheb4UbLffUxyTdHczS27-o,40
@@ -138,15 +109,7 @@
 examples/wheel/lib/module_with_data.py,sha256=8s0Khhcqz3yVsBKv2IB5u4l4TMKh7-c_V6p65WVHPms,637
 examples/wheel/lib/simple_module.py,sha256=z2hwciab_XPNIBNH8B1Q5fYgnJvQTeYf0ZQJpY8yLLY,637
 examples/wheel/main.py,sha256=sgg5iWN_9inYBjm6_Zw27hYdmo-l24fA-2rfphT-IlY,909
-"""
-                self.assertIn(
-                    record_contents,
-                    [
-                        rbe_expected_contents,
-                        unix_expected_contents,
-                    ],
-                )
-
+""")
             self.assertEqual(
                 wheel_contents,
                 b"""\
@@ -156,44 +119,9 @@
 Tag: py3-none-any
 """,
             )
-            if platform.system() == "Windows":
-                self.assertEqual(
-                    metadata_contents,
-                    b"""\
-Metadata-Version: 2.1
-Name: example_customized
-Version: 0.0.1
-Author: Example Author with non-ascii characters: \xc3\x85\xc2\xbc\xc3\x83\xc2\xb3\xc3\x85\xc2\x82w
-Author-email: example@example.com
-Home-page: www.example.com
-License: Apache 2.0
-Classifier: License :: OSI Approved :: Apache Software License
-Classifier: Intended Audience :: Developers
-Requires-Dist: pytest
-
-This is a sample description of a wheel.
-""",
-                )
-            else:
-                # TODO: The non-ascii characters in the METADATA file are interpreted differently on the
-                # ubuntu16_rbe hosts in comparison to other unix platforms. This should not be the case
-                # and the code should be updated to account for this.
-                rbe_expected_contents = b"""\
-Metadata-Version: 2.1
-Name: example_customized
-Version: 0.0.1
-Author: Example Author with non-ascii characters: \xc3\x85\xc2\xbc\xc3\x83\xc2\xb3\xc3\x85\xc2\x82w
-Author-email: example@example.com
-Home-page: www.example.com
-License: Apache 2.0
-Classifier: License :: OSI Approved :: Apache Software License
-Classifier: Intended Audience :: Developers
-Requires-Dist: pytest
-
-This is a sample description of a wheel.
-"""
-
-                unix_expected_contents = b"""\
+            self.assertEqual(
+                metadata_contents,
+                b"""\
 Metadata-Version: 2.1
 Name: example_customized
 Version: 0.0.1
@@ -206,14 +134,7 @@
 Requires-Dist: pytest
 
 This is a sample description of a wheel.
-"""
-                self.assertIn(
-                    metadata_contents,
-                    [
-                        rbe_expected_contents,
-                        unix_expected_contents,
-                    ],
-                )
+""")
             self.assertEqual(
                 entry_point_contents,
                 b"""\
diff --git a/python/packaging.bzl b/python/packaging.bzl
index 22d1f5b..6d7a901 100644
--- a/python/packaging.bzl
+++ b/python/packaging.bzl
@@ -153,7 +153,6 @@
     args.add("--name", ctx.attr.distribution)
     args.add("--version", version)
     args.add("--python_tag", ctx.attr.python_tag)
-    args.add("--python_requires", ctx.attr.python_requires)
     args.add("--abi", ctx.attr.abi)
     args.add("--platform", ctx.attr.platform)
     args.add("--out", outfile)
@@ -168,28 +167,42 @@
 
     args.add("--input_file_list", packageinputfile)
 
-    extra_headers = []
-    if ctx.attr.author:
-        extra_headers.append("Author: %s" % ctx.attr.author)
-    if ctx.attr.author_email:
-        extra_headers.append("Author-email: %s" % ctx.attr.author_email)
-    if ctx.attr.homepage:
-        extra_headers.append("Home-page: %s" % ctx.attr.homepage)
-    if ctx.attr.license:
-        extra_headers.append("License: %s" % ctx.attr.license)
+    # Note: Description file is not embedded into metadata.txt yet,
+    # it will be done later by wheelmaker script.
+    metadata_file = ctx.actions.declare_file(ctx.attr.name + ".metadata.txt")
+    metadata_contents = ["Metadata-Version: 2.1"]
+    metadata_contents.append("Name: %s" % ctx.attr.distribution)
+    metadata_contents.append("Version: %s" % version)
 
-    for h in extra_headers:
-        args.add("--header", h)
+    if ctx.attr.author:
+        metadata_contents.append("Author: %s" % ctx.attr.author)
+    if ctx.attr.author_email:
+        metadata_contents.append("Author-email: %s" % ctx.attr.author_email)
+    if ctx.attr.homepage:
+        metadata_contents.append("Home-page: %s" % ctx.attr.homepage)
+    if ctx.attr.license:
+        metadata_contents.append("License: %s" % ctx.attr.license)
 
     for c in ctx.attr.classifiers:
-        args.add("--classifier", c)
+        metadata_contents.append("Classifier: %s" % c)
 
-    for r in ctx.attr.requires:
-        args.add("--requires", r)
+    if ctx.attr.python_requires:
+        metadata_contents.append("Requires-Python: %s" % ctx.attr.python_requires)
+    for requirement in ctx.attr.requires:
+        metadata_contents.append("Requires-Dist: %s" % requirement)
 
-    for option, requirements in ctx.attr.extra_requires.items():
-        for r in requirements:
-            args.add("--extra_requires", r + ";" + option)
+    for option, option_requirements in sorted(ctx.attr.extra_requires.items()):
+        metadata_contents.append("Provides-Extra: %s" % option)
+        for requirement in option_requirements:
+            metadata_contents.append(
+                "Requires-Dist: %s; extra == '%s'" % (requirement, option),
+            )
+    ctx.actions.write(
+        output = metadata_file,
+        content = "\n".join(metadata_contents) + "\n",
+    )
+    other_inputs.append(metadata_file)
+    args.add("--metadata_file", metadata_file)
 
     # Merge console_scripts into entry_points.
     entrypoints = dict(ctx.attr.entry_points)  # Copy so we can mutate it
@@ -334,7 +347,9 @@
         doc = "List of optional requirements for this package",
     ),
     "requires": attr.string_list(
-        doc = "List of requirements for this package",
+        doc = ("List of requirements for this package. See the section on " +
+               "[Declaring required dependency](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#declaring-dependencies) " +
+               "for details and examples of the format of this argument."),
     ),
 }
 
@@ -366,7 +381,7 @@
         doc = "A list of strings describing the categories for the package. For valid classifiers see https://pypi.org/classifiers",
     ),
     "description_file": attr.label(
-        doc = "A file containing text describing the package in a single line.",
+        doc = "A file containing text describing the package.",
         allow_single_file = True,
     ),
     "extra_distinfo_files": attr.label_keyed_string_dict(
@@ -383,10 +398,7 @@
     ),
     "python_requires": attr.string(
         doc = (
-            "A string specifying what other distributions need to be installed " +
-            "when this one is. See the section on " +
-            "[Declaring required dependency](https://setuptools.readthedocs.io/en/latest/userguide/dependency_management.html#declaring-dependencies) " +
-            "for details and examples of the format of this argument."
+            "Python versions required by this distribution, e.g. '>=3.5,<3.7'"
         ),
         default = "",
     ),
diff --git a/tools/wheelmaker.py b/tools/wheelmaker.py
index 4e03680..d517900 100644
--- a/tools/wheelmaker.py
+++ b/tools/wheelmaker.py
@@ -167,39 +167,11 @@
             wheel_contents += "Tag: %s\n" % tag
         self.add_string(self.distinfo_path("WHEEL"), wheel_contents)
 
-    def add_metadata(
-        self,
-        extra_headers,
-        description,
-        classifiers,
-        python_requires,
-        requires,
-        extra_requires,
-    ):
+    def add_metadata(self, metadata, description):
         """Write METADATA file to the distribution."""
         # https://www.python.org/dev/peps/pep-0566/
         # https://packaging.python.org/specifications/core-metadata/
-        metadata = []
-        metadata.append("Metadata-Version: 2.1")
-        metadata.append("Name: %s" % self._name)
-        metadata.append("Version: %s" % self._version)
-        metadata.extend(extra_headers)
-        for classifier in classifiers:
-            metadata.append("Classifier: %s" % classifier)
-        if python_requires:
-            metadata.append("Requires-Python: %s" % python_requires)
-        for requirement in requires:
-            metadata.append("Requires-Dist: %s" % requirement)
-
-        extra_requires = sorted(extra_requires.items())
-        for option, option_requires in extra_requires:
-            metadata.append("Provides-Extra: %s" % option)
-            for requirement in option_requires:
-                metadata.append(
-                    "Requires-Dist: %s; extra == '%s'" % (requirement, option)
-                )
-
-        metadata = "\n".join(metadata) + "\n\n"
+        metadata += "\n"
         # setuptools seems to insert UNKNOWN as description when none is
         # provided.
         metadata += description if description else "UNKNOWN"
@@ -303,25 +275,15 @@
         action="append",
         default=[],
         help="Path prefix to be stripped from input package files' path. "
-        "Can be supplied multiple times. "
-        "Evaluated in order.",
+             "Can be supplied multiple times. Evaluated in order.",
     )
 
     wheel_group = parser.add_argument_group("Wheel metadata")
     wheel_group.add_argument(
-        "--header",
-        action="append",
-        help="Additional headers to be embedded in the package metadata. "
-        "Can be supplied multiple times.",
-    )
-    wheel_group.add_argument(
-        "--classifier",
-        action="append",
-        help="Classifiers to embed in package metadata. "
-        "Can be supplied multiple times",
-    )
-    wheel_group.add_argument(
-        "--python_requires", help="Version of python that the wheel will work with"
+        "--metadata_file",
+        type=Path,
+        help="Contents of the METADATA file (before appending contents of "
+             "--description_file)",
     )
     wheel_group.add_argument(
         "--description_file", help="Path to the file with package description"
@@ -352,21 +314,6 @@
         "dist-info directory. Can be supplied multiple times.",
     )
 
-    requirements_group = parser.add_argument_group("Package requirements")
-    requirements_group.add_argument(
-        "--requires",
-        type=str,
-        action="append",
-        help="List of package requirements. Can be supplied multiple times.",
-    )
-    requirements_group.add_argument(
-        "--extra_requires",
-        type=str,
-        action="append",
-        help="List of optional requirements in a 'requirement;option name'. "
-        "Can be supplied multiple times.",
-    )
-
     build_group = parser.add_argument_group("Building requirements")
     build_group.add_argument(
         "--volatile_status_file",
@@ -434,32 +381,24 @@
         description = None
         if arguments.description_file:
             if sys.version_info[0] == 2:
-                with open(arguments.description_file, "rt") as description_file:
+                with open(arguments.description_file,
+                          "rt") as description_file:
                     description = description_file.read()
             else:
-                with open(
-                    arguments.description_file, "rt", encoding="utf-8"
-                ) as description_file:
+                with open(arguments.description_file, "rt",
+                          encoding="utf-8") as description_file:
                     description = description_file.read()
 
-        extra_requires = collections.defaultdict(list)
-        if arguments.extra_requires:
-            for extra in arguments.extra_requires:
-                req, option = extra.rsplit(";", 1)
-                extra_requires[option].append(req)
-        classifiers = arguments.classifier or []
-        python_requires = arguments.python_requires or ""
-        requires = arguments.requires or []
-        extra_headers = arguments.header or []
+        metadata = None
+        if sys.version_info[0] == 2:
+            with open(arguments.metadata_file, "rt") as metadata_file:
+                metadata = metadata_file.read()
+        else:
+            with open(arguments.metadata_file, "rt",
+                      encoding="utf-8") as metadata_file:
+                metadata = metadata_file.read()
 
-        maker.add_metadata(
-            extra_headers=extra_headers,
-            description=description,
-            classifiers=classifiers,
-            python_requires=python_requires,
-            requires=requires,
-            extra_requires=extra_requires,
-        )
+        maker.add_metadata(metadata=metadata, description=description)
 
         if arguments.entry_points_file:
             maker.add_file(