diff --git a/.bazelrc b/.bazelrc
index d30b1fa1ca..b7698b896e 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -231,11 +231,12 @@ common:v8-target-arm64 --@v8//bazel/config:v8_target_cpu=arm64
 # the matching runtime objects.
 common:rusty-v8-upstream-libcxx --@v8//:v8_use_rusty_v8_custom_libcxx=True
 
-# Native Windows archive builds inherit the runner's MSVC SDK environment.
+# Native Windows MSVC builds inherit the runner's MSVC SDK environment.
 # Client environment capture and repository discovery happen before target
 # transitions, so these runner settings cannot live in runtime_package.bzl.
-# The archive target selects its own MSVC host platform and native toolchains.
+# Hermetic LLVM targets the GNU ABI on Windows even on an MSVC platform.
 build:ci-windows-msvc --repo_env=BAZEL_DO_NOT_DETECT_CPP_TOOLCHAIN=0
+build:ci-windows-msvc --extra_toolchains=@local_config_cc//:cc-toolchain-x64_windows,@local_config_cc//:cc-toolchain-arm64_windows
 build:ci-windows-msvc --action_env=PATH
 build:ci-windows-msvc --host_action_env=PATH
 build:ci-windows-msvc --action_env=INCLUDE
diff --git a/.github/workflows/bazel.yml b/.github/workflows/bazel.yml
index ede5a7f070..2f4b09deb1 100644
--- a/.github/workflows/bazel.yml
+++ b/.github/workflows/bazel.yml
@@ -251,8 +251,8 @@ jobs:
   test-windows-native-main:
     # Native Windows Bazel tests are slower and frequently approach the
     # 30-minute PR budget. Run this only for post-merge commits to main and give
-    # it a larger timeout.
-    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
+    # it a larger timeout. Also allow manual runs for native toolchain changes.
+    if: (github.event_name == 'push' && github.ref == 'refs/heads/main') || github.event_name == 'workflow_dispatch'
     timeout-minutes: 40
     runs-on:
       group: ${{ github.event.repository.name }}-runners
@@ -290,6 +290,7 @@ jobs:
 
           bazel_test_args=(
             test
+            --config=ci-windows-msvc
             --platforms=//:windows_x86_64_msvc
             --test_tag_filters=-argument-comment-lint
             --test_verbose_timeout_warnings