Index: llvm/utils/lit/lit/llvm/config.py
===================================================================
--- llvm/utils/lit/lit/llvm/config.py
+++ llvm/utils/lit/lit/llvm/config.py
@@ -1,3 +1,4 @@
+import itertools
 import os
 import platform
 import re
@@ -24,9 +25,15 @@
             features.add('system-windows')
 
             # Seek sane tools in directories and set to $PATH.
-            path = self.lit_config.getToolsPath(config.lit_tools_dir,
-                                                config.environment['PATH'],
-                                                ['cmp.exe', 'grep.exe', 'sed.exe'])
+            path = None
+            lit_tools_dir = getattr(config, 'lit_tools_dir', None)
+            if lit_tools_dir:
+                path = self.lit_config.getToolsPath(lit_tools_dir,
+                                                    config.environment['PATH'],
+                                                    ['cmp.exe', 'grep.exe', 'sed.exe',
+                                                    'diff.exe', 'echo.exe'])
+            if path is None:
+                path = self._find_git_windows_unix_tools()
             if path is not None:
                 self.with_environment('PATH', path, append_path=True)
             # Many tools behave strangely if these environment variables aren't set.
@@ -115,6 +122,36 @@
                 self.with_environment(
                     'DYLD_INSERT_LIBRARIES', gmalloc_path_str)
 
+    def _find_git_windows_unix_tools(self):
+        assert(sys.platform == 'win32')
+        import winreg
+
+        # Search both the 64 and 32-bit hives, as well as HKLM + HKCU
+        masks = [winreg.KEY_WOW64_32KEY, winreg.KEY_WOW64_64KEY]
+        hives = [winreg.HKEY_LOCAL_MACHINE, winreg.HKEY_CURRENT_USER]
+        for mask, hive in itertools.product(masks, hives):
+            try:
+                with winreg.OpenKey(hive, r"SOFTWARE\GitForWindows", access=winreg.KEY_READ | mask) as key:
+                    try:
+                        install_root, _ = winreg.QueryValueEx(key, 'InstallPath')
+                    except:
+                        continue
+
+                    if not install_root:
+                        continue
+                    candidate_path = os.path.join(install_root, 'usr', 'bin')
+                    files = [os.path.join(candidate_path, x) for x in ['echo.exe', 'grep.exe', 'sed.exe', 'diff.exe']]
+                    # If any of the files doesn't exist, keep searching.
+                    if any(not os.path.exists(x) for x in files):
+                        continue
+
+                    # We found it, stop enumerating.
+                    return candidate_path
+            except:
+                continue
+
+        return None
+
     def with_environment(self, variable, value, append_path=False):
         if append_path:
             # For paths, we should be able to take a list of them and process all