diff --git a/python/private/BUILD.bazel b/python/private/BUILD.bazel
index c99b040..75e48bc 100644
--- a/python/private/BUILD.bazel
+++ b/python/private/BUILD.bazel
@@ -19,7 +19,7 @@
 
 filegroup(
     name = "distribution",
-    srcs = glob(["**"]),
+    srcs = glob(["**"]) + ["//python/private/proto:distribution"],
     visibility = ["//python:__pkg__"],
 )
 
diff --git a/python/private/proto/BUILD b/python/private/proto/BUILD
new file mode 100644
index 0000000..8483d19
--- /dev/null
+++ b/python/private/proto/BUILD
@@ -0,0 +1,32 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+load("@rules_proto//proto:defs.bzl", "proto_lang_toolchain")
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])  # Apache 2.0
+
+filegroup(
+    name = "distribution",
+    srcs = glob(["**"]),
+    visibility = ["//python/private:__pkg__"],
+)
+
+proto_lang_toolchain(
+    name = "python_toolchain",
+    command_line = "--python_out=%s",
+    progress_message = "Generating Python proto_library %{label}",
+    runtime = "@com_google_protobuf//:protobuf_python",
+)
diff --git a/python/private/proto/py_proto_library.bzl b/python/private/proto/py_proto_library.bzl
new file mode 100644
index 0000000..ef5f2ca
--- /dev/null
+++ b/python/private/proto/py_proto_library.bzl
@@ -0,0 +1,191 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""The implementation of the `py_proto_library` rule and its aspect."""
+
+load("@rules_proto//proto:defs.bzl", "ProtoInfo", "proto_common")
+load("//python:defs.bzl", "PyInfo")
+
+ProtoLangToolchainInfo = proto_common.ProtoLangToolchainInfo
+
+_PyProtoInfo = provider(
+    doc = "Encapsulates information needed by the Python proto rules.",
+    fields = {
+        "runfiles_from_proto_deps": """
+            (depset[File]) Files from the transitive closure implicit proto
+            dependencies""",
+        "transitive_sources": """(depset[File]) The Python sources.""",
+    },
+)
+
+def _filter_provider(provider, *attrs):
+    return [dep[provider] for attr in attrs for dep in attr if provider in dep]
+
+def _py_proto_aspect_impl(target, ctx):
+    """Generates and compiles Python code for a proto_library.
+
+    The function runs protobuf compiler on the `proto_library` target generating
+    a .py file for each .proto file.
+
+    Args:
+      target: (Target) A target providing `ProtoInfo`. Usually this means a
+         `proto_library` target, but not always; you must expect to visit
+         non-`proto_library` targets, too.
+      ctx: (RuleContext) The rule context.
+
+    Returns:
+      ([_PyProtoInfo]) Providers collecting transitive information about
+      generated files.
+    """
+
+    _proto_library = ctx.rule.attr
+
+    # Check Proto file names
+    for proto in target[ProtoInfo].direct_sources:
+        if proto.is_source and "-" in proto.dirname:
+            fail("Cannot generate Python code for a .proto whose path contains '-' ({}).".format(
+                proto.path,
+            ))
+
+    proto_lang_toolchain_info = ctx.attr._aspect_proto_toolchain[ProtoLangToolchainInfo]
+    api_deps = [proto_lang_toolchain_info.runtime]
+
+    generated_sources = []
+    proto_info = target[ProtoInfo]
+    if proto_info.direct_sources:
+        # Generate py files
+        generated_sources = proto_common.declare_generated_files(
+            actions = ctx.actions,
+            proto_info = proto_info,
+            extension = "_pb2.py",
+            name_mapper = lambda name: name.replace("-", "_").replace(".", "/"),
+        )
+
+        proto_common.compile(
+            actions = ctx.actions,
+            proto_info = proto_info,
+            proto_lang_toolchain_info = proto_lang_toolchain_info,
+            generated_files = generated_sources,
+            plugin_output = ctx.bin_dir.path,
+        )
+
+    # Generated sources == Python sources
+    python_sources = generated_sources
+
+    deps = _filter_provider(_PyProtoInfo, getattr(_proto_library, "deps", []))
+    runfiles_from_proto_deps = depset(
+        transitive = [dep[DefaultInfo].default_runfiles.files for dep in api_deps] +
+                     [dep.runfiles_from_proto_deps for dep in deps],
+    )
+    transitive_sources = depset(
+        direct = python_sources,
+        transitive = [dep.transitive_sources for dep in deps],
+    )
+
+    return [
+        _PyProtoInfo(
+            runfiles_from_proto_deps = runfiles_from_proto_deps,
+            transitive_sources = transitive_sources,
+        ),
+    ]
+
+_py_proto_aspect = aspect(
+    implementation = _py_proto_aspect_impl,
+    attrs = {
+        "_aspect_proto_toolchain": attr.label(
+            default = ":python_toolchain",
+        ),
+    },
+    attr_aspects = ["deps"],
+    required_providers = [ProtoInfo],
+    provides = [_PyProtoInfo],
+)
+
+def _py_proto_library_rule(ctx):
+    """Merges results of `py_proto_aspect` in `deps`.
+
+    Args:
+      ctx: (RuleContext) The rule context.
+    Returns:
+      ([PyInfo, DefaultInfo, OutputGroupInfo])
+    """
+    if not ctx.attr.deps:
+        fail("'deps' attribute mustn't be empty.")
+
+    pyproto_infos = _filter_provider(_PyProtoInfo, ctx.attr.deps)
+    default_outputs = depset(
+        transitive = [info.transitive_sources for info in pyproto_infos],
+    )
+
+    return [
+        DefaultInfo(
+            files = default_outputs,
+            default_runfiles = ctx.runfiles(transitive_files = depset(
+                transitive =
+                    [default_outputs] +
+                    [info.runfiles_from_proto_deps for info in pyproto_infos],
+            )),
+        ),
+        OutputGroupInfo(
+            default = depset(),
+        ),
+        PyInfo(
+            transitive_sources = default_outputs,
+            # Proto always produces 2- and 3- compatible source files
+            has_py2_only_sources = False,
+            has_py3_only_sources = False,
+        ),
+    ]
+
+py_proto_library = rule(
+    implementation = _py_proto_library_rule,
+    doc = """
+      Use `py_proto_library` to generate Python libraries from `.proto` files.
+
+      The convention is to name the `py_proto_library` rule `foo_py_pb2`,
+      when it is wrapping `proto_library` rule `foo_proto`.
+
+      `deps` must point to a `proto_library` rule.
+
+      Example:
+
+```starlark
+py_library(
+    name = "lib",
+    deps = [":foo_py_pb2"],
+)
+
+py_proto_library(
+    name = "foo_py_pb2",
+    deps = [":foo_proto"],
+)
+
+proto_library(
+    name = "foo_proto",
+    srcs = ["foo.proto"],
+)
+```""",
+    attrs = {
+        "deps": attr.label_list(
+            doc = """
+              The list of `proto_library` rules to generate Python libraries for.
+
+              Usually this is just the one target: the proto library of interest.
+              It can be any target providing `ProtoInfo`.""",
+            providers = [ProtoInfo],
+            aspects = [_py_proto_aspect],
+        ),
+    },
+    provides = [PyInfo],
+)
diff --git a/python/proto.bzl b/python/proto.bzl
new file mode 100644
index 0000000..3f455ae
--- /dev/null
+++ b/python/proto.bzl
@@ -0,0 +1,21 @@
+# Copyright 2022 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Python proto library.
+"""
+
+load("//python/private/proto:py_proto_library.bzl", _py_proto_library = "py_proto_library")
+
+py_proto_library = _py_proto_library