diff --git a/llvm/test/Other/lit-quoting.txt b/llvm/test/Other/lit-quoting.txt
--- a/llvm/test/Other/lit-quoting.txt
+++ b/llvm/test/Other/lit-quoting.txt
@@ -1,2 +1,9 @@
-RUN: echo "\"" | FileCheck %s
-CHECK: {{^"$}}
+RUN: echo "\"" | FileCheck %s --check-prefix=CHECK1
+RUN: echo '"' | FileCheck %s --check-prefix=CHECK1
+RUN: echo 'a[b\c' | FileCheck %s --check-prefix=CHECK2
+RUN: echo "a[b\\c" | FileCheck %s --check-prefix=CHECK2
+RUN: echo 'a\b\\c\\\\d' | FileCheck %s --check-prefix=CHECK3
+RUN: echo "a\\b\\\\c\\\\\\\\d" | FileCheck %s --check-prefix=CHECK3
+CHECK1: {{^"$}}
+CHECK2: {{^a\[b\\c$}}
+CHECK3: {{^a\\b\\\\c\\\\\\\\d$}}
diff --git a/llvm/utils/lit/lit/TestRunner.py b/llvm/utils/lit/lit/TestRunner.py
--- a/llvm/utils/lit/lit/TestRunner.py
+++ b/llvm/utils/lit/lit/TestRunner.py
@@ -4,6 +4,7 @@
 import itertools
 import getopt
 import os, signal, subprocess, sys
+import pefile
 import re
 import stat
 import platform
@@ -177,7 +178,29 @@
         result.extend(expand_glob(arg, cwd))
     return result
 
-def quote_windows_command(seq):
+def _memoize(f):
+    cache = {}  # Intentionally unbounded, see applySubstitutions()
+    def memoized(x):
+        if x not in cache:
+            cache[x] = f(x)
+        return cache[x]
+    return memoized
+
+@_memoize
+def _caching_is_msys(exe):
+    try:
+        pe = pefile.PE(exe, fast_load=True)
+        pe.is_driver() # This loads DIRECTORY_ENTRY_IMPORT after fast_load
+        if hasattr(pe, 'DIRECTORY_ENTRY_IMPORT'):
+            for imp in pe.DIRECTORY_ENTRY_IMPORT:
+                dll = imp.dll.decode('utf-8', 'ignore').lower()
+                if dll == 'msys-2.0.dll':
+                    return True
+        return False
+    except:
+        return False
+
+def quote_windows_command(seq, executable):
     """
     Reimplement Python's private subprocess.list2cmdline for MSys compatibility
 
@@ -190,11 +213,36 @@
     differences.
 
     We use the same algorithm from MSDN as CPython
-    (http://msdn.microsoft.com/en-us/library/17w5ykft.aspx), but we treat more
-    characters as needing quoting, such as double quotes themselves.
+    (http://msdn.microsoft.com/en-us/library/17w5ykft.aspx), but we try to
+    detect if the target executable is an MSys executable, and if it is,
+    and the argument looks like it contains chars that trigger globbing,
+    we quote it and double the backslashes in it.
+
+    Unfortunately, it seems to be impossible to quote complex arguments in a
+    way that both the MSVC CRT and MSys would interpret the same way
+    consistently. Quoting arguments affect how MSys interpret certain chars
+    like backslashes. One can also set the env var MSYS=noglob to inhibit
+    the globbing process (which affects how chars are quoted), but that
+    breaks a few cases where the globbing handling is required:
+
+      Input           MSys app       MSys app           Regular win32 app
+                      sees           with noglob sees   sees
+    1 a[b\c           a[bc           a[b\c              a[b\c
+    2 a\b\\c\\\\d     a\b\\c\\\\d    a\b\\c\\\\d        a\b\\c\\\\d
+    3 a\"b            a\b            a\b                a"b
+    4 "a[b\c"         a[b\c          a[b\c              a[b\c
+    5 "a\b\\c\\\\d"   a\b\c\\d       a\b\\c\\\\d        a\b\\c\\\\d
+    6 "a\"b"          a"b            a\b                a"b
+
+    Chars like [ trigger globbing, which break handling of lone backslashes
+    (case 1). Quoting fixes handling of lone backslashes (case 4), as does
+    disabling globbing. Quoting with globbing breaks handling of multiple
+    backslashes (case 5), and disabling globbing breaks handling of escaped
+    double quotes (case 6).
     """
     result = []
     needquote = False
+    is_msys = _caching_is_msys(executable)
     for arg in seq:
         bs_buf = []
 
@@ -204,6 +252,19 @@
 
         # This logic differs from upstream list2cmdline.
         needquote = (" " in arg) or ("\t" in arg) or ("\"" in arg) or not arg
+
+        if not needquote and is_msys:
+            needquote = any(c in arg for c in "?*[\"\'(){}")
+
+        if needquote and is_msys:
+            result.append('"')
+            for c in arg:
+                if c == '\\' or c == '"':
+                    result.append('\\')
+                result.append(c)
+            result.append('"')
+            continue
+
         if needquote:
             result.append('"')
 
@@ -768,7 +829,7 @@
         # On Windows, do our own command line quoting for better compatibility
         # with some core utility distributions.
         if kIsWindows:
-            args = quote_windows_command(args)
+            args = quote_windows_command(args, executable)
 
         try:
             procs.append(subprocess.Popen(args, cwd=cmd_shenv.cwd,
@@ -1150,14 +1211,6 @@
             ])
     return substitutions
 
-def _memoize(f):
-    cache = {}  # Intentionally unbounded, see applySubstitutions()
-    def memoized(x):
-        if x not in cache:
-            cache[x] = f(x)
-        return cache[x]
-    return memoized
-
 @_memoize
 def _caching_re_compile(r):
     return re.compile(r)