@filipesilva I have made some progress on this recently.
Now with Bazel built from HEAD, symlink tree will be available on Windows when you pass `--experimental_enable_runfiles`. 
Can you try if it helps with https://github.com/bazelbuild/bazel/issues/5926? @filipesilva Just found a bug when dealing with long path, sending a fix now.
Have you thought of using a `typedef`? I think that'd be more type-safe and more readable than a macro. Have you thought of using an unnamed namespace? That restricts visibility and the binary will not export these symbols.

(See https://google.github.io/styleguide/cppguide.html#Unnamed_Namespaces_and_Static_Variables) What's the reason for using `explicit`? The error message is confusing, "INPUT RUNFILES" can be understood as "a list of input runfiles". What's the intended meaning? Could you clarify the message? I think the argument type does not need to be a const reference. Can you think of a more efficient approach? What does the rest of the loop do when `use_metadata` is false? What's the reason to store an entry when `target` is empty? Is this call necessary? Doesn't `ifstream`'s destructor close the file? String comparison should ignore casing. This call fails if the directory is not empty. Is that expected? Why can we ignore it? Have you considered using a foreach-loop? `CreateFileW` returns `INVALID_HANDLE_VALUE` on error. Please compare `h` to that instead of to `0`. type-safety: use `FALSE` `FALSE` (BOOL) instead of `false` (bool). Do you need to do this before every test, or would it suffice to export these envvars just once? Why is there one more symlink on Windows? You are calling `readlink $i` multiple times. Could you cache its result? why is there one more symlink on Windows? same here about `readlink $i` Good idea. Replaced it with typedef and moved it into the class definition. Good to know that, thanks! Done I copied from the Linux version build-runfiles.cc, but I think it's unnecessary, so removed. If `use_metadata` is false, it means every line in the manifest is a runfile entry, then the loop will read each of them and add them in the manifest map. If `use_metadata` is true, it will skip all lines with even line number, because they are metadata lines.
See https://github.com/bazelbuild/bazel/blob/master/src/main/tools/build-runfiles.cc#L144 Bazel sometimes need to create empty files under the runfiles tree. For example, for python binary, `__init__.py` is needed under every directory. Storing an entry with an empty `target` indicates we need to create such a file when creating the runfiles tree. Indeed, removed. `AsAbsoluteWindowsPath` will convert the path to a normalized path, than means both of them are already in lower case. Here we are deleting a symlink, so it won't fail even the target directory is not empty. Because if the directory is not empty, it means it contains some symlinks already pointing to the correct targets (we just called `ScanTreeAndPrune`). Then this directory shouldn't be removed in the first place. It's better to check if the directory is empty before deleting it, but there's not simple kernel API for that. Good idea! Done. Done. Done Indeed, it's confusing. Updated. Right, once is enough. Because for shell binary, we build both `bin` and `bin.exe`, but on Linux we only build `bin` Yes, done. Answered in above comment. Done. Thanks. Please add this as a code comment. Thanks! Could you add this explanation to the code? Thanks! The convention in manpages is to put mandatory arguments in angle brackets, e.g. `<manifest_file>`. I think doing that here would increase readability. The name `use_metadata` confuses me, it suggests that the function should use (or ignore) the metadata. WDYT? If you agree, can you think of a better name? Could you add this as a comment? Could you add this to the code as a comment? Thanks, please add it as a comment here too. Indeed, `ignore_metadata` is better. Just realized `use_metadata` is also the flag name and used some other places in Java code. Let me instead add a comment here to clarify. Done. Done Done! Done Done
Use symlinked runfiles on Windows when supported
### Description of the problem / feature request:

On Windows Bazel sets `RUNFILES_MANIFEST_ONLY` to `1` and does not generate symlinks to runfiles. This does not change if the current user can create symlinks.

On recent Windows 10 versions it is possible to enable symlinks for all users:

> Now in Windows 10 Creators Update, a user (with admin rights) can first enable Developer Mode, and then any user on the machine can run the mklink command without elevating a command-line console.

More details can be found in https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/

The feature I am requesting is to generate symlink to runfiles on Windows when supported by the current user.

### Feature requests: what underlying problem are you trying to solve with this feature?

Creating rules with windows support is not trivial (https://github.com/bazelbuild/bazel/issues/3726#issuecomment-329504506). 

Using symlinks on windows when available should make many existing rules work on Windows without having to resolve runfiles via the manifest, given the user has symlink support. 

On systems Windows without symlink support enabled, looking up the runfiles would still be necessary.

Related to https://github.com/bazelbuild/bazel/issues/3726, https://github.com/bazelbuild/bazel/issues/3889, https://github.com/bazelbuild/bazel/issues/1212

/cc @alexeagle
src/main/cpp/util/BUILD src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java src/main/tools/BUILD src/main/tools/build-runfiles-windows.cc
src/main/cpp/util/BUILD src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java src/main/tools/BUILD src/main/tools/build-runfiles-windows.cc
src/test/py/bazel/runfiles_test.py src/test/shell/integration/BUILD src/test/shell/integration/runfiles_test.sh
diff --git a/src/main/cpp/util/BUILD b/src/main/cpp/util/BUILD
index 9df4e558d8f472..bc799aba338af7 100644
--- a/src/main/cpp/util/BUILD
+++ b/src/main/cpp/util/BUILD
@@ -55,6 +55,7 @@ cc_library(
     visibility = [
         ":ijar",
         "//src/test/cpp/util:__pkg__",
+        "//src/main/tools:__pkg__",
         "//src/tools/launcher:__subpackages__",
         "//src/tools/singlejar:__pkg__",
         "//third_party/def_parser:__pkg__",
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 7590d6aa696d28..2b58187dd7005d 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -1167,10 +1167,6 @@ public void reportInvalidOptions(EventHandler reporter) {
       fragment.reportInvalidOptions(reporter, this.buildOptions);
     }
 
-    if (OS.getCurrent() == OS.WINDOWS && runfilesEnabled()) {
-      reporter.handle(Event.error("building runfiles is not supported on Windows"));
-    }
-
     if (options.outputDirectoryName != null) {
       reporter.handle(Event.error(
           "The internal '--output directory name' option cannot be used on the command line"));
diff --git a/src/main/tools/BUILD b/src/main/tools/BUILD
index e67d67baaa6953..8362c0c0b6dd22 100644
--- a/src/main/tools/BUILD
+++ b/src/main/tools/BUILD
@@ -48,6 +48,7 @@ cc_binary(
         "//src/conditions:windows": ["build-runfiles-windows.cc"],
         "//conditions:default": ["build-runfiles.cc"],
     }),
+    deps = ["//src/main/cpp/util:filesystem"],
 )
 
 cc_binary(
diff --git a/src/main/tools/build-runfiles-windows.cc b/src/main/tools/build-runfiles-windows.cc
index ea4eed189aab26..db01284e0c2635 100644
--- a/src/main/tools/build-runfiles-windows.cc
+++ b/src/main/tools/build-runfiles-windows.cc
@@ -12,16 +12,399 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#include <windows.h>
 #include <iostream>
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <string.h>
+#include <unordered_map>
 
-int main(int argc, char** argv) {
-  // TODO(bazel-team): decide whether we need build-runfiles at all on Windows.
-  // Implement this program if so; make sure we don't run it on Windows if not.
-  std::cout << "ERROR: build-runfiles is not (yet?) implemented on Windows."
-            << std::endl
-            << "Called with args:" << std::endl;
-  for (int i = 0; i < argc; ++i) {
-    std::cout << "argv[" << i << "]=(" << argv[i] << ")" << std::endl;
+#include "src/main/cpp/util/path_platform.h"
+#include "src/main/cpp/util/file_platform.h"
+#include "src/main/cpp/util/strings.h"
+
+using std::ifstream;
+using std::unordered_map;
+using std::string;
+using std::wstring;
+using std::stringstream;
+
+#ifndef SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE
+#define SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE 0x2
+#endif
+
+#ifndef SYMBOLIC_LINK_FLAG_DIRECTORY
+#define SYMBOLIC_LINK_FLAG_DIRECTORY 0x1
+#endif
+
+namespace {
+
+const wchar_t *manifest_filename;
+const wchar_t *runfiles_base_dir;
+
+string GetLastErrorString() {
+  DWORD last_error = GetLastError();
+  if (last_error == 0) {
+    return string();
+  }
+
+  char* message_buffer;
+  size_t size = FormatMessageA(
+      FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
+          FORMAT_MESSAGE_IGNORE_INSERTS,
+      NULL, last_error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+      (LPSTR)&message_buffer, 0, NULL);
+
+  stringstream result;
+  result << "(error: " << last_error << "): " << message_buffer;
+  LocalFree(message_buffer);
+  return result.str();
+}
+
+void die(const wchar_t* format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  fputws(L"build-runfiles error: ", stderr);
+  vfwprintf(stderr, format, ap);
+  va_end(ap);
+  fputwc(L'\n', stderr);
+  fputws(L"manifest file name: ", stderr);
+  fputws(manifest_filename, stderr);
+  fputwc(L'\n', stderr);
+  fputws(L"runfiles base directory: ", stderr);
+  fputws(runfiles_base_dir, stderr);
+  fputwc(L'\n', stderr);
+  exit(1);
+}
+
+wstring AsAbsoluteWindowsPath(const wchar_t* path) {
+  wstring wpath;
+  string error;
+  if (!blaze_util::AsAbsoluteWindowsPath(path, &wpath, &error)) {
+    die(L"Couldn't convert %s to absolute Windows path: %hs", path,
+        error.c_str());
+  }
+  return wpath;
+}
+
+bool DoesDirectoryPathExist(const wchar_t* path) {
+  DWORD dwAttrib = GetFileAttributesW(AsAbsoluteWindowsPath(path).c_str());
+
+  return (dwAttrib != INVALID_FILE_ATTRIBUTES &&
+          (dwAttrib & FILE_ATTRIBUTE_DIRECTORY));
+}
+
+wstring GetParentDirFromPath(const wstring& path) {
+  return path.substr(0, path.find_last_of(L"\\/"));
+}
+
+inline void Trim(wstring& str){
+  str.erase(0, str.find_first_not_of(' '));
+  str.erase(str.find_last_not_of(' ') + 1);
+}
+
+} // namespace
+
+class RunfilesCreator {
+  typedef std::unordered_map<std::wstring, std::wstring> ManifestFileMap;
+
+ public:
+  RunfilesCreator(const wstring &manifest_path,
+                           const wstring &runfiles_output_base)
+      : manifest_path_(manifest_path),
+        runfiles_output_base_(runfiles_output_base) {
+    SetupOutputBase();
+    if (!SetCurrentDirectoryW(runfiles_output_base_.c_str())) {
+      die(L"SetCurrentDirectoryW failed (%s): %hs",
+          runfiles_output_base_.c_str(), GetLastErrorString().c_str());
+    }
+  }
+
+  void ReadManifest(bool allow_relative, bool ignore_metadata) {
+    ifstream manifest_file(
+      AsAbsoluteWindowsPath(manifest_path_.c_str()).c_str());
+
+    if (!manifest_file) {
+      die(L"Couldn't open MANIFEST file: %s", manifest_path_.c_str());
+    }
+
+    string line;
+    int lineno = 0;
+    while (getline(manifest_file, line)) {
+      lineno++;
+      // Skip metadata lines. They are used solely for
+      // dependency checking.
+      if (ignore_metadata && lineno % 2 == 0) {
+        continue;
+      }
+
+      size_t space_pos = line.find_first_of(' ');
+      wstring wline = blaze_util::CstringToWstring(line);
+      wstring link, target;
+      if (space_pos == string::npos) {
+        link = wline;
+        target = wstring();
+      } else {
+        link = wline.substr(0, space_pos);
+        target = wline.substr(space_pos + 1);
+      }
+
+      // Removing leading and trailing spaces
+      Trim(link);
+      Trim(target);
+
+
+      // We sometimes need to create empty files under the runfiles tree.
+      // For example, for python binary, __init__.py is needed under every directory.
+      // Storing an entry with an empty target indicates we need to create such a
+      // file when creating the runfiles tree.
+      if (!allow_relative && !target.empty()
+          && !blaze_util::IsAbsolute(target)) {
+        die(L"Target cannot be relative path: %hs", line.c_str());
+      }
+
+      link = AsAbsoluteWindowsPath(link.c_str());
+
+      manifest_file_map.insert(make_pair(link, target));
+    }
+  }
+
+  void CreateRunfiles() {
+    bool symlink_needs_privilege =
+      DoesCreatingSymlinkNeedAdminPrivilege(runfiles_output_base_);
+    ScanTreeAndPrune(runfiles_output_base_);
+    CreateFiles(symlink_needs_privilege);
+    CopyManifestFile();
   }
-  return 1;
+
+ private:
+  void SetupOutputBase() {
+    if (!DoesDirectoryPathExist(runfiles_output_base_.c_str())) {
+      MakeDirectoriesOrDie(runfiles_output_base_);
+    }
+  }
+
+  void MakeDirectoriesOrDie(const wstring& path) {
+    if (!blaze_util::MakeDirectoriesW(path, 0755)) {
+      die(L"MakeDirectoriesW failed (%s): %hs",
+          path.c_str(), GetLastErrorString().c_str());
+    }
+  }
+
+  void RemoveDirectoryOrDie(const wstring& path) {
+    if (!RemoveDirectoryW(path.c_str())) {
+      die(L"RemoveDirectoryW failed (%s): %hs", GetLastErrorString().c_str());
+    }
+  }
+
+  void DeleteFileOrDie(const wstring& path) {
+    SetFileAttributesW(path.c_str(),
+                       GetFileAttributesW(path.c_str()) & ~FILE_ATTRIBUTE_READONLY);
+    if (!DeleteFileW(path.c_str())) {
+      die(L"DeleteFileW failed (%s): %hs",
+          path.c_str(), GetLastErrorString().c_str());
+    }
+  }
+
+  bool DoesCreatingSymlinkNeedAdminPrivilege(const wstring& runfiles_base_dir) {
+    wstring dummy_link = runfiles_base_dir + L"\\dummy_link";
+    wstring dummy_target = runfiles_base_dir + L"\\dummy_target";
+
+    // Try creating symlink without admin privilege.
+    if (CreateSymbolicLinkW(dummy_link.c_str(), dummy_target.c_str(),
+                            SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE)) {
+      DeleteFileOrDie(dummy_link);
+      return false;
+    }
+
+    // Try creating symlink with admin privilege
+    if (CreateSymbolicLinkW(dummy_link.c_str(), dummy_target.c_str(), 0)) {
+      DeleteFileOrDie(dummy_link);
+      return true;
+    }
+
+    // If we couldn't create symlink, print out an error message and exit.
+    if (GetLastError() == ERROR_PRIVILEGE_NOT_HELD) {
+      die(L"CreateSymbolicLinkW failed:\n%hs\n",
+          "Bazel needs to create symlink for building runfiles tree.\n"
+          "Creating symlink on Windows requires either of the following:\n"
+          "    1. Program is running with elevated privileges (Admin rights).\n"
+          "    2. The system version is Windows 10 Creators Update (1703) or later and "
+          "developer mode is enabled.",
+          GetLastErrorString().c_str());
+    } else {
+      die(L"CreateSymbolicLinkW failed: %hs", GetLastErrorString().c_str());
+    }
+
+    return true;
+  }
+
+  // This function scan the current directory, remove all files/symlinks/directories that
+  // are not presented in manifest file.
+  // If a symlink already exists and points to the correct target, this function erases
+  // its entry from manifest_file_map, so that we won't recreate it.
+  void ScanTreeAndPrune(const wstring& path) {
+    static const wstring kDot(L".");
+    static const wstring kDotDot(L"..");
+
+    WIN32_FIND_DATAW metadata;
+    HANDLE handle = ::FindFirstFileW((path + L"\\*").c_str(), &metadata);
+    if (handle == INVALID_HANDLE_VALUE) {
+      return;  // directory does not exist or is empty
+    }
+
+    do {
+      if (kDot != metadata.cFileName && kDotDot != metadata.cFileName) {
+        wstring subpath = path + L"\\" + metadata.cFileName;
+        bool is_dir =
+            (metadata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) != 0;
+        bool is_symlink =
+            (metadata.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT) != 0;
+        if (is_symlink) {
+          wstring target;
+          if (!blaze_util::ReadSymlinkW(subpath, &target)) {
+            die(L"ReadSymlinkW failed (%s): %hs",
+                subpath.c_str(), GetLastErrorString().c_str());
+          };
+
+          subpath = AsAbsoluteWindowsPath(subpath.c_str());
+          target = AsAbsoluteWindowsPath(target.c_str());
+          ManifestFileMap::iterator expected_target =
+              manifest_file_map.find(subpath);
+
+          if (expected_target == manifest_file_map.end()
+              || expected_target->second.empty()
+              // Both paths are normalized paths in lower case, we can compare them directly.
+              || target != AsAbsoluteWindowsPath(expected_target->second.c_str())
+              || blaze_util::IsDirectoryW(target) != is_dir) {
+            if (is_dir) {
+              RemoveDirectoryOrDie(subpath);
+            } else {
+              DeleteFileOrDie(subpath);
+            }
+          } else {
+            manifest_file_map.erase(expected_target);
+          }
+        } else {
+          if (is_dir) {
+            ScanTreeAndPrune(subpath);
+            // If the directory is empty, then we remove the directory.
+            // Otherwise RemoveDirectory will fail with ERROR_DIR_NOT_EMPTY,
+            // which we can just ignore.
+            // Because if the directory is not empty, it means it contains some symlinks
+            // already pointing to the correct targets (we just called ScanTreeAndPrune).
+            // Then this directory shouldn't be removed in the first place.
+            if (!RemoveDirectoryW(subpath.c_str())
+                && GetLastError() != ERROR_DIR_NOT_EMPTY) {
+              die(L"RemoveDirectoryW failed (%s): %hs",
+                  subpath.c_str(), GetLastErrorString().c_str());
+            }
+          } else {
+            DeleteFileOrDie(subpath);
+          }
+        }
+      }
+    } while (::FindNextFileW(handle, &metadata));
+    ::FindClose(handle);
+  }
+
+  void CreateFiles(bool creating_symlink_needs_admin_privilege) {
+    DWORD privilege_flag = creating_symlink_needs_admin_privilege
+                           ? 0
+                           : SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE;
+
+    for (const auto &it : manifest_file_map) {
+      // Ensure the parent directory exists
+      wstring parent_dir = GetParentDirFromPath(it.first);
+      if (!DoesDirectoryPathExist(parent_dir.c_str())) {
+        MakeDirectoriesOrDie(parent_dir);
+      }
+
+      if (it.second.empty()) {
+        // Create an empty file
+        HANDLE h = CreateFileW(it.first.c_str(),     // name of the file
+                               GENERIC_WRITE, // open for writing
+                               0,            // sharing mode, none in this case
+                               0,            // use default security descriptor
+                               CREATE_ALWAYS, // overwrite if exists
+                               FILE_ATTRIBUTE_NORMAL,
+                               0);
+        if (h != INVALID_HANDLE_VALUE) {
+          CloseHandle(h);
+        } else {
+          die(L"CreateFileW failed (%s): %hs",
+              it.first.c_str(), GetLastErrorString().c_str());
+        }
+      } else {
+        DWORD create_dir = 0;
+        if (blaze_util::IsDirectoryW(it.second.c_str())) {
+          create_dir = SYMBOLIC_LINK_FLAG_DIRECTORY;
+        }
+        if (!CreateSymbolicLinkW(it.first.c_str(),
+                                 it.second.c_str(),
+                                 privilege_flag | create_dir)) {
+          die(L"CreateSymbolicLinkW failed (%s -> %s): %hs",
+              it.first.c_str(), it.second.c_str(),
+              GetLastErrorString().c_str());
+        }
+      }
+    }
+  }
+
+  void CopyManifestFile() {
+    wstring new_manifest_file = runfiles_output_base_ + L"\\MANIFEST";
+    if (!CopyFileW(manifest_path_.c_str(),
+                   new_manifest_file.c_str(),
+                   /*bFailIfExists=*/ FALSE
+                  )) {
+      die(L"CopyFileW failed (%s -> %s): %hs",
+          manifest_path_.c_str(), new_manifest_file.c_str(),
+          GetLastErrorString().c_str());
+    }
+  }
+
+ private:
+  wstring manifest_path_;
+  wstring runfiles_output_base_;
+  ManifestFileMap manifest_file_map;
+};
+
+int wmain(int argc, wchar_t** argv) {
+  argc--; argv++;
+  bool allow_relative = false;
+  bool ignore_metadata = false;
+
+  while (argc >= 1) {
+    if (wcscmp(argv[0], L"--allow_relative") == 0) {
+      allow_relative = true;
+      argc--; argv++;
+    } else if (wcscmp(argv[0], L"--use_metadata") == 0) {
+      // If --use_metadata is passed, it means manifest file contains metadata lines,
+      // which we should ignore when reading manifest file.
+      ignore_metadata = true;
+      argc--; argv++;
+    } else {
+      break;
+    }
+  }
+
+  if (argc != 2) {
+    fprintf(stderr, "usage: [--allow_relative] [--use_metadata] "
+            "<manifest_file> <runfiles_base_dir>\n");
+    return 1;
+  }
+
+  manifest_filename = argv[0];
+  runfiles_base_dir = argv[1];
+
+  wstring manifest_absolute_path = AsAbsoluteWindowsPath(manifest_filename);
+  wstring output_base_absolute_path = AsAbsoluteWindowsPath(runfiles_base_dir);
+
+  RunfilesCreator runfiles_creator(manifest_absolute_path,
+                                   output_base_absolute_path);
+  runfiles_creator.ReadManifest(allow_relative, ignore_metadata);
+  runfiles_creator.CreateRunfiles();
+
+  return 0;
 }

diff --git a/src/test/py/bazel/runfiles_test.py b/src/test/py/bazel/runfiles_test.py
index 50506f63918e8a..36aba0d7678642 100644
--- a/src/test/py/bazel/runfiles_test.py
+++ b/src/test/py/bazel/runfiles_test.py
@@ -21,16 +21,6 @@
 
 class RunfilesTest(test_base.TestBase):
 
-  def testAttemptToBuildRunfilesOnWindows(self):
-    if not self.IsWindows():
-      self.skipTest("only applicable to Windows")
-    self.ScratchFile("WORKSPACE")
-    exit_code, _, stderr = self.RunBazel(
-        ["build", "--experimental_enable_runfiles"])
-    self.assertNotEqual(exit_code, 0)
-    self.assertIn("building runfiles is not supported on Windows",
-                  "\n".join(stderr))
-
   def _AssertRunfilesLibraryInBazelToolsRepo(self, family, lang_name):
     for s, t, exe in [("WORKSPACE.mock", "WORKSPACE",
                        False), ("foo/BUILD.mock", "foo/BUILD",
diff --git a/src/test/shell/integration/BUILD b/src/test/shell/integration/BUILD
index 5501058918bb29..efdde9ec93af03 100644
--- a/src/test/shell/integration/BUILD
+++ b/src/test/shell/integration/BUILD
@@ -29,11 +29,12 @@ sh_test(
     name = "runfiles_test",
     size = "medium",
     srcs = ["runfiles_test.sh"],
-    data = [":test-deps"],
+    data = [
+        ":test-deps",
+        "@bazel_tools//tools/bash/runfiles",
+    ],
     tags = [
         "local",
-        # no_windows: this test exercises the symlink-based runfiles tree.
-        "no_windows",
     ],
 )
 
diff --git a/src/test/shell/integration/runfiles_test.sh b/src/test/shell/integration/runfiles_test.sh
index cb2e88627e0438..fd85be9849fd82 100755
--- a/src/test/shell/integration/runfiles_test.sh
+++ b/src/test/shell/integration/runfiles_test.sh
@@ -16,18 +16,59 @@
 #
 # An end-to-end test that Bazel produces runfiles trees as expected.
 
-# Load the test setup defined in the parent directory
-CURRENT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-source "${CURRENT_DIR}/../integration_test_setup.sh" \
+# --- begin runfiles.bash initialization ---
+# Copy-pasted from Bazel's Bash runfiles library (tools/bash/runfiles/runfiles.bash).
+set -euo pipefail
+if [[ ! -d "${RUNFILES_DIR:-/dev/null}" && ! -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
+  if [[ -f "$0.runfiles_manifest" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles_manifest"
+  elif [[ -f "$0.runfiles/MANIFEST" ]]; then
+    export RUNFILES_MANIFEST_FILE="$0.runfiles/MANIFEST"
+  elif [[ -f "$0.runfiles/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
+    export RUNFILES_DIR="$0.runfiles"
+  fi
+fi
+if [[ -f "${RUNFILES_DIR:-/dev/null}/bazel_tools/tools/bash/runfiles/runfiles.bash" ]]; then
+  source "${RUNFILES_DIR}/bazel_tools/tools/bash/runfiles/runfiles.bash"
+elif [[ -f "${RUNFILES_MANIFEST_FILE:-/dev/null}" ]]; then
+  source "$(grep -m1 "^bazel_tools/tools/bash/runfiles/runfiles.bash " \
+            "$RUNFILES_MANIFEST_FILE" | cut -d ' ' -f 2-)"
+else
+  echo >&2 "ERROR: cannot find @bazel_tools//tools/bash/runfiles:runfiles.bash"
+  exit 1
+fi
+# --- end runfiles.bash initialization ---
+
+source "$(rlocation "io_bazel/src/test/shell/integration_test_setup.sh")" \
   || { echo "integration_test_setup.sh not found!" >&2; exit 1; }
 
+case "$(uname -s | tr [:upper:] [:lower:])" in
+msys*|mingw*|cygwin*)
+  declare -r is_windows=true
+  ;;
+*)
+  declare -r is_windows=false
+  ;;
+esac
+
+if "$is_windows"; then
+  export MSYS_NO_PATHCONV=1
+  export MSYS2_ARG_CONV_EXCL="*"
+  export EXT=".exe"
+  export EXTRA_BUILD_FLAGS="--experimental_enable_runfiles --build_python_zip=0"
+else
+  export EXT=""
+  export EXTRA_BUILD_FLAGS=""
+fi
+
 #### SETUP #############################################################
 
 set -e
 
-function set_up() {
-  mkdir -p pkg
-  cd pkg
+function create_pkg() {
+  local -r pkg=$1
+  mkdir -p $pkg
+  cd $pkg
 
   mkdir -p a/b c/d e/f/g x/y
   touch py.py a/b/no_module.py c/d/one_module.py c/__init__.py e/f/g/ignored.py x/y/z.sh
@@ -40,7 +81,9 @@ function set_up() {
 #### TESTS #############################################################
 
 function test_hidden() {
-  cat > pkg/BUILD << EOF
+  local -r pkg=$FUNCNAME
+  create_pkg $pkg
+  cat > $pkg/BUILD << EOF
 py_binary(name = "py",
           srcs = [ "py.py" ],
           data = [ "e/f",
@@ -49,19 +92,21 @@ genrule(name = "hidden",
         outs = [ "e/f/g/hidden.py" ],
         cmd = "touch \$@")
 EOF
-  bazel build pkg:py >&$TEST_log 2>&1 || fail "build failed"
+  bazel build $pkg:py $EXTRA_BUILD_FLAGS >&$TEST_log 2>&1 || fail "build failed"
 
   # we get a warning that hidden.py is inaccessible
-  expect_log_once "pkg/e/f/g/hidden.py obscured by pkg/e/f "
+  expect_log_once "${pkg}/e/f/g/hidden.py obscured by ${pkg}/e/f "
 }
 
 function test_foo_runfiles() {
+  local -r pkg=$FUNCNAME
+  create_pkg $pkg
 cat > BUILD << EOF
 py_library(name = "root",
            srcs = ["__init__.py"],
            visibility = ["//visibility:public"])
 EOF
-cat > pkg/BUILD << EOF
+cat > $pkg/BUILD << EOF
 sh_binary(name = "foo",
           srcs = [ "x/y/z.sh" ],
           data = [ ":py",
@@ -74,9 +119,10 @@ py_binary(name = "py",
                    "e/f/g/ignored.py" ],
           deps = ["//:root"])
 EOF
-  bazel build pkg:foo >&$TEST_log || fail "build failed"
+  bazel build $pkg:foo $EXTRA_BUILD_FLAGS >&$TEST_log || fail "build failed"
+  workspace_root=$PWD
 
-  cd ${PRODUCT_NAME}-bin/pkg/foo.runfiles
+  cd ${PRODUCT_NAME}-bin/$pkg/foo${EXT}.runfiles
 
   # workaround until we use assert/fail macros in the tests below
   touch $TEST_TMPDIR/__fail
@@ -88,10 +134,10 @@ EOF
   cd ${WORKSPACE_NAME}
 
   # these are real directories
-  test \! -L pkg
-  test    -d pkg
+  test \! -L $pkg
+  test    -d $pkg
 
-  cd pkg
+  cd $pkg
   test \! -L a
   test    -d a
   test \! -L a/b
@@ -133,17 +179,110 @@ EOF
 
   # that accounts for everything
   cd ../..
-  assert_equals  9 $(find ${WORKSPACE_NAME} -type l | wc -l)
-  assert_equals  4 $(find ${WORKSPACE_NAME} -type f | wc -l)
-  assert_equals  9 $(find ${WORKSPACE_NAME} -type d | wc -l)
-  assert_equals 22 $(find ${WORKSPACE_NAME} | wc -l)
-  assert_equals 13 $(wc -l < MANIFEST)
+  # For shell binary, we build both `bin` and `bin.exe`, but on Linux we only build `bin`
+  # That's why we have one more symlink on Windows.
+  if "$is_windows"; then
+    assert_equals 10 $(find ${WORKSPACE_NAME} -type l | wc -l)
+    assert_equals  4 $(find ${WORKSPACE_NAME} -type f | wc -l)
+    assert_equals  9 $(find ${WORKSPACE_NAME} -type d | wc -l)
+    assert_equals 23 $(find ${WORKSPACE_NAME} | wc -l)
+    assert_equals 14 $(wc -l < MANIFEST)
+  else
+    assert_equals  9 $(find ${WORKSPACE_NAME} -type l | wc -l)
+    assert_equals  4 $(find ${WORKSPACE_NAME} -type f | wc -l)
+    assert_equals  9 $(find ${WORKSPACE_NAME} -type d | wc -l)
+    assert_equals 22 $(find ${WORKSPACE_NAME} | wc -l)
+    assert_equals 13 $(wc -l < MANIFEST)
+  fi
 
   for i in $(find ${WORKSPACE_NAME} \! -type d); do
-    if readlink "$i" > /dev/null; then
-      echo "$i $(readlink "$i")" >> ${TEST_TMPDIR}/MANIFEST2
+    target="$(readlink "$i" || true)"
+    if [[ -z "$target" ]]; then
+      echo "$i " >> ${TEST_TMPDIR}/MANIFEST2
     else
+      if "$is_windows"; then
+        echo "$i $(cygpath -m $target)" >> ${TEST_TMPDIR}/MANIFEST2
+      else
+        echo "$i $target" >> ${TEST_TMPDIR}/MANIFEST2
+      fi
+    fi
+  done
+  sort MANIFEST > ${TEST_TMPDIR}/MANIFEST_sorted
+  sort ${TEST_TMPDIR}/MANIFEST2 > ${TEST_TMPDIR}/MANIFEST2_sorted
+  diff -u ${TEST_TMPDIR}/MANIFEST_sorted ${TEST_TMPDIR}/MANIFEST2_sorted
+
+  # Rebuild the same target with a new dependency.
+  cd "$workspace_root"
+cat > $pkg/BUILD << EOF
+sh_binary(name = "foo",
+          srcs = [ "x/y/z.sh" ],
+          data = [ "e/f" ])
+EOF
+  bazel build $pkg:foo $EXTRA_BUILD_FLAGS >&$TEST_log || fail "build failed"
+
+  cd ${PRODUCT_NAME}-bin/$pkg/foo${EXT}.runfiles
+
+  # workaround until we use assert/fail macros in the tests below
+  touch $TEST_TMPDIR/__fail
+
+  # output manifest exists and is non-empty
+  test    -f MANIFEST
+  test    -s MANIFEST
+
+  cd ${WORKSPACE_NAME}
+
+  # these are real directories
+  test \! -L $pkg
+  test    -d $pkg
+
+  # these directory should not exist anymore
+  test \! -e a
+  test \! -e c
+
+  cd $pkg
+  test \! -L e
+  test    -d e
+  test \! -L x
+  test    -d x
+  test \! -L x/y
+  test    -d x/y
+
+  # these are symlinks to the source tree
+  test    -L foo
+  test    -L x/y/z.sh
+  test    -L e/f
+  test    -d e/f
+
+  # that accounts for everything
+  cd ../..
+  # For shell binary, we build both `bin` and `bin.exe`, but on Linux we only build `bin`
+  # That's why we have one more symlink on Windows.
+  if "$is_windows"; then
+    assert_equals  4 $(find ${WORKSPACE_NAME} -type l | wc -l)
+    assert_equals  0 $(find ${WORKSPACE_NAME} -type f | wc -l)
+    assert_equals  5 $(find ${WORKSPACE_NAME} -type d | wc -l)
+    assert_equals  9 $(find ${WORKSPACE_NAME} | wc -l)
+    assert_equals  4 $(wc -l < MANIFEST)
+  else
+    assert_equals  3 $(find ${WORKSPACE_NAME} -type l | wc -l)
+    assert_equals  0 $(find ${WORKSPACE_NAME} -type f | wc -l)
+    assert_equals  5 $(find ${WORKSPACE_NAME} -type d | wc -l)
+    assert_equals  8 $(find ${WORKSPACE_NAME} | wc -l)
+    assert_equals  3 $(wc -l < MANIFEST)
+  fi
+
+  rm -f ${TEST_TMPDIR}/MANIFEST
+  rm -f ${TEST_TMPDIR}/MANIFEST2
+  for i in $(find ${WORKSPACE_NAME} \! -type d); do
+    target="$(readlink "$i" || true)"
+    if [[ -z "$target" ]]; then
       echo "$i " >> ${TEST_TMPDIR}/MANIFEST2
+    else
+      if "$is_windows"; then
+        echo "$i $(cygpath -m $target)" >> ${TEST_TMPDIR}/MANIFEST2
+      else
+        echo "$i $target" >> ${TEST_TMPDIR}/MANIFEST2
+      fi
     fi
   done
   sort MANIFEST > ${TEST_TMPDIR}/MANIFEST_sorted
@@ -166,15 +305,15 @@ EOF
   cat > thing.cc <<EOF
 int main() { return 0; }
 EOF
-  bazel build //:thing &> $TEST_log || fail "Build failed"
-  [[ -d ${PRODUCT_NAME}-bin/thing.runfiles/foo ]] || fail "foo not found"
+  bazel build //:thing $EXTRA_BUILD_FLAGS &> $TEST_log || fail "Build failed"
+  [[ -d ${PRODUCT_NAME}-bin/thing${EXT}.runfiles/foo ]] || fail "foo not found"
 
   cat > WORKSPACE <<EOF
 workspace(name = "bar")
 EOF
-  bazel build //:thing &> $TEST_log || fail "Build failed"
-  [[ -d ${PRODUCT_NAME}-bin/thing.runfiles/bar ]] || fail "bar not found"
-  [[ ! -d ${PRODUCT_NAME}-bin/thing.runfiles/foo ]] \
+  bazel build //:thing $EXTRA_BUILD_FLAGS &> $TEST_log || fail "Build failed"
+  [[ -d ${PRODUCT_NAME}-bin/thing${EXT}.runfiles/bar ]] || fail "bar not found"
+  [[ ! -d ${PRODUCT_NAME}-bin/thing${EXT}.runfiles/foo ]] \
     || fail "Old foo still found"
 }
 
