diff --git a/python/private/get_local_runtime_info.py b/python/private/get_local_runtime_info.py
index e0eab962d6..a4f622700b 100644
--- a/python/private/get_local_runtime_info.py
+++ b/python/private/get_local_runtime_info.py
@@ -268,7 +268,9 @@ def _get_base_executable() -> str:
     "implementation_name": sys.implementation.name,
     "base_executable": _get_base_executable(),
     "sys_platform": sys.platform,
-    "platform_machine": platform.machine(),
+    # Normalize to lowercase: on Windows, platform.machine() returns uppercase
+    # "AMD64" / "ARM64", whereas PEP 508 and toolchains expect lowercase.
+    "platform_machine": platform.machine().lower(),
 }
 data.update(_get_python_library_info(_get_base_executable()))
 print(json.dumps(data))
diff --git a/python/private/local_runtime_repo_setup.bzl b/python/private/local_runtime_repo_setup.bzl
index 62e46e4b98..05ca6228e0 100644
--- a/python/private/local_runtime_repo_setup.bzl
+++ b/python/private/local_runtime_repo_setup.bzl
@@ -137,6 +137,10 @@ def define_local_runtime_toolchain_impl(
         hdrs = [":includes"],
         defines = defines,  # NOTE: Users should define Py_LIMITED_API=3
         srcs = abi3_libraries + additional_dlls,
+        deps = select({
+            "@bazel_tools//src/conditions:windows": [":abi3_interface"],
+            "//conditions:default": [],
+        }),
     )
 
     cc_library(
@@ -144,6 +148,10 @@ def define_local_runtime_toolchain_impl(
         hdrs = [":includes"],
         defines = defines,
         srcs = libraries + additional_dlls,
+        deps = select({
+            "@bazel_tools//src/conditions:windows": [":interface"],
+            "//conditions:default": [],
+        }),
     )
 
     # runtime configuration
diff --git a/tests/integration/local_toolchains/BUILD.bazel b/tests/integration/local_toolchains/BUILD.bazel
index 20ee7bcfe6..ae99e7cf2f 100644
--- a/tests/integration/local_toolchains/BUILD.bazel
+++ b/tests/integration/local_toolchains/BUILD.bazel
@@ -13,9 +13,8 @@
 # limitations under the License.
 
 load("@bazel_skylib//rules:common_settings.bzl", "string_flag")
-load("@rules_cc//cc:cc_library.bzl", "cc_library")
 load("@rules_python//python:py_test.bzl", "py_test")
-load(":py_extension.bzl", "py_extension")
+load("@rules_python//python/cc:py_extension.bzl", "py_extension")
 
 py_test(
     name = "local_runtime_test",
@@ -60,28 +59,24 @@ string_flag(
 )
 
 # Build rules to generate a python extension.
-cc_library(
-    name = "echo_ext_cc",
-    testonly = True,
-    srcs = ["echo_ext.cc"],
-    deps = [
-        "@rules_python//python/cc:current_py_cc_headers",
-    ],
-    alwayslink = True,
-)
-
 py_extension(
     name = "echo_ext",
     testonly = True,
+    srcs = ["echo_ext.cc"],
     copts = select({
         "@rules_cc//cc/compiler:msvc-cl": [],
         "//conditions:default": ["-fvisibility=hidden"],
     }),
-    deps = [":echo_ext_cc"],
+    imports = ["."],
 )
 
 py_test(
     name = "echo_test",
     srcs = ["echo_test.py"],
+    # Make this test better respect pyenv/local Python DLLs on Windows
+    env_inherit = [
+        "PYENV_VERSION",
+        "PATH",
+    ],
     deps = [":echo_ext"],
 )
diff --git a/tests/integration/local_toolchains/echo_test.py b/tests/integration/local_toolchains/echo_test.py
index 17121e0f17..655205fe29 100644
--- a/tests/integration/local_toolchains/echo_test.py
+++ b/tests/integration/local_toolchains/echo_test.py
@@ -5,4 +5,4 @@
 
 class ExtensionTest(unittest.TestCase):
     def test_echo_extension(self):
-        self.assertEqual(echo_ext.echo(42, "str"), tuple(42, "str"))
+        self.assertEqual(echo_ext.echo(42, "str"), (42, "str"))
diff --git a/tests/integration/local_toolchains/py_extension.bzl b/tests/integration/local_toolchains/py_extension.bzl
deleted file mode 100644
index 5d37fd7824..0000000000
--- a/tests/integration/local_toolchains/py_extension.bzl
+++ /dev/null
@@ -1,154 +0,0 @@
-# Copyright 2025 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.
-
-"""Macro to build a python C/C++ extension.
-
-There are variants of py_extension in many other projects, such as:
-* https://github.com/protocolbuffers/protobuf/tree/main/python/py_extension.bzl
-* https://github.com/google/riegeli/blob/master/python/riegeli/py_extension.bzl
-* https://github.com/pybind/pybind11_bazel/blob/master/build_defs.bzl
-
-The issue for a generic verion is:
-* https://github.com/bazel-contrib/rules_python/issues/824
-"""
-
-load("@bazel_skylib//rules:copy_file.bzl", "copy_file")
-load("@rules_cc//cc:cc_binary.bzl", "cc_binary")
-load("@rules_python//python:defs.bzl", "py_library")
-
-def py_extension(
-        *,
-        name,
-        deps = None,
-        linkopts = None,
-        imports = None,
-        visibility = None,
-        **kwargs):
-    """Creates a Python module implemented in C++.
-
-    A Python extension has 2 essential parts:
-      1.  An internal shared object / pyd package for the extension, `name.pyd`/`name.so`
-      2.  The py_library target for the extension.`
-
-    Python modules can depend on a py_extension.
-
-    Args:
-      name: `str`. Name for this target.  This is typically the module name.
-      deps: `list`. Required. C++ libraries to link into the module.
-      linkopts: `list`. Linking options for the shared library.
-      imports: `list`. Additional imports for the py_library rule.
-      visibility: `str`. Visibility for target.
-      **kwargs:  Additional options for the cc_library rule.
-    """
-    if not name:
-        fail("py_extension requires a name")
-    if not deps:
-        fail("py_extension requires a non-empty deps attribute")
-    if "linkshared" in kwargs:
-        fail("py_extension attribute linkshared not allowed")
-
-    if not linkopts:
-        linkopts = []
-
-    testonly = kwargs.get("testonly")
-    tags = kwargs.pop("tags", [])
-
-    cc_binary_so_name = name + ".so"
-    cc_binary_dll_name = name + ".dll"
-    cc_binary_pyd_name = name + ".pyd"
-    linker_script_name = name + ".lds"
-    linker_script_name_rule = name + "_lds"
-    shared_objects_name = name + "__shared_objects"
-
-    # On Unix, restrict symbol visibility.
-    exported_symbol = "PyInit_" + name
-
-    # Generate linker script used on non-macOS unix platforms.
-    native.genrule(
-        name = linker_script_name_rule,
-        outs = [linker_script_name],
-        cmd = "\n".join([
-            "cat <<'EOF' >$@",
-            "{",
-            "  global: " + exported_symbol + ";",
-            "  local: *;",
-            "};",
-            "EOF",
-        ]),
-    )
-
-    for cc_binary_name in [cc_binary_dll_name, cc_binary_so_name]:
-        cur_linkopts = linkopts
-        cur_deps = deps
-        if cc_binary_name == cc_binary_so_name:
-            cur_linkopts = linkopts + select({
-                "@platforms//os:macos": [
-                    # Avoid undefined symbol errors for CPython symbols that
-                    # will be resolved at runtime.
-                    "-undefined",
-                    "dynamic_lookup",
-                    # On macOS, the linker does not support version scripts.  Use
-                    # the `-exported_symbol` option instead to restrict symbol
-                    # visibility.
-                    "-Wl,-exported_symbol",
-                    # On macOS, the symbol starts with an underscore.
-                    "-Wl,_" + exported_symbol,
-                ],
-                # On non-macOS unix, use a version script to restrict symbol
-                # visibility.
-                "//conditions:default": [
-                    "-Wl,--version-script",
-                    "-Wl,$(location :" + linker_script_name + ")",
-                ],
-            })
-            cur_deps = cur_deps + select({
-                "@platforms//os:macos": [],
-                "//conditions:default": [linker_script_name],
-            })
-
-        cc_binary(
-            name = cc_binary_name,
-            linkshared = True,
-            visibility = ["//visibility:private"],
-            deps = cur_deps,
-            tags = tags + ["manual"],
-            linkopts = cur_linkopts,
-            **kwargs
-        )
-
-    copy_file(
-        name = cc_binary_pyd_name + "__pyd_copy",
-        src = ":" + cc_binary_dll_name,
-        out = cc_binary_pyd_name,
-        visibility = visibility,
-        tags = ["manual"],
-        testonly = testonly,
-    )
-
-    native.filegroup(
-        name = shared_objects_name,
-        data = select({
-            "@platforms//os:windows": [":" + cc_binary_pyd_name],
-            "//conditions:default": [":" + cc_binary_so_name],
-        }),
-        testonly = testonly,
-    )
-    py_library(
-        name = name,
-        data = [":" + shared_objects_name],
-        imports = imports,
-        tags = tags,
-        testonly = testonly,
-        visibility = visibility,
-    )