Index: source/Core/Mangled.cpp
===================================================================
--- source/Core/Mangled.cpp
+++ source/Core/Mangled.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 
+#include <algorithm>
 // FreeBSD9-STABLE requires this to know about size_t in cxxabi.h
 #include <cstddef>
 #if defined(_MSC_VER)
@@ -4995,6 +4996,32 @@
 
 using namespace lldb_private;
 
+#if defined(_MSC_VER)
+static void
+insert_spaces_after_commas (char *s, std::size_t max)
+{
+    assert(max > 0);
+    const std::size_t length = strlen(s);
+    const int comma_count = std::count(s, s + length, ',');
+    if (comma_count > 0 && length + comma_count < max - 1)
+    {
+        // Start at the end and work backwards until the target location catches
+        // up to the source location.  (We already know that everything from the
+        // beginning of the string to that point is identical.)
+        const char *source = s + length;
+        char *target = s + length + comma_count;
+        while (target > source)
+        {
+            if (*source == ',')
+            {
+                *target-- = ' ';
+            }
+            *target-- = *source--;
+        }
+    }
+}
+#endif
+
 static inline bool
 cstring_is_mangled (const char *s)
 {
@@ -5231,11 +5258,14 @@
                 if (!demangled_name)
                     demangled_name = __cxa_demangle (mangled_cstr, NULL, NULL, NULL);
 #elif defined(_MSC_VER)
-                char *demangled_name = (char *)::malloc(1024);
-                ::ZeroMemory(demangled_name, 1024);
-                DWORD result = ::UnDecorateSymbolName(mangled_cstr, demangled_name, 1023,
+                const std::size_t demangled_buffer_size = 1024;
+                char *demangled_name = (char *)::malloc(demangled_buffer_size);
+                ::ZeroMemory(demangled_name, demangled_buffer_size);
+                DWORD result = ::UnDecorateSymbolName(mangled_cstr, demangled_name,
+                                                      demangled_buffer_size - 1,
                                                       UNDNAME_NO_ACCESS_SPECIFIERS |       // Strip public, private, protected keywords
                                                           UNDNAME_NO_ALLOCATION_LANGUAGE | // Strip __thiscall, __stdcall, etc keywords
+                                                          UNDNAME_NO_FUNCTION_RETURNS |    // Strip function return types
                                                           UNDNAME_NO_THROW_SIGNATURES |    // Strip throw() specifications
                                                           UNDNAME_NO_MEMBER_TYPE |         // Strip virtual, static, etc specifiers
                                                           UNDNAME_NO_MS_KEYWORDS           // Strip all MS extension keywords
@@ -5245,6 +5275,14 @@
                     free (demangled_name);
                     demangled_name = nullptr;
                 }
+                else
+                {
+                    // UnDecorateSymbolName doesn't put spaces after commas, but
+                    // the built-in demangler does, so add them for consistency.
+                    // Besides, our tests expect them.
+                    insert_spaces_after_commas(demangled_name, demangled_buffer_size);
+                }
+
 #else
                 char *demangled_name = abi::__cxa_demangle (mangled_cstr, NULL, NULL, NULL);
 #endif
Index: test/functionalities/abbreviation/TestAbbreviations.py
===================================================================
--- test/functionalities/abbreviation/TestAbbreviations.py
+++ test/functionalities/abbreviation/TestAbbreviations.py
@@ -148,19 +148,14 @@
                                  "at main.cpp\:25",
                                  "stop reason = breakpoint 2.1" ])
 
-        # ARCH, if not specified, defaults to x86_64.
-        self.runCmd("dis -f")
+        # Recognizing output as disassembly in an architecture-independent way
+        # is tricky.  Since we're just trying to verify that `dis -f` does the
+        # same things as `disassemble -f`, we'll run both commands and compare
+        # the output.  This doesn't validate anything about the disassembly
+        # itself; there are other tests for that.
+        self.runCmd("disassemble -f")
         disassembly = self.res.GetOutput()
-        if self.getArchitecture() in ["", 'x86_64', 'i386']:
-            # hey! we shouldn't have a software breakpoint in here
-            self.assertFalse("int3" in disassembly)
-            self.expect(disassembly, exe=False,
-                        startstr = "a.out`sum(int, int)",
-                        substrs = [' mov',
-                                   ' addl ',
-                                   'ret'])
-        else:
-            self.fail('unimplemented for arch = "{arch}"'.format(arch=self.getArchitecture()))
+        self.expect("dis -f", startstr = disassembly)
 
         self.expect("i d l main.cpp",
                     patterns = ["Line table for .*main.cpp in `a.out"])
Index: test/make/Makefile.rules
===================================================================
--- test/make/Makefile.rules
+++ test/make/Makefile.rules
@@ -30,8 +30,22 @@
 LLDB_BASE_DIR := $(THIS_FILE_DIR)../../
 
 #----------------------------------------------------------------------
-# If ARCH is not defined, default to x86_64.
 # If OS is not defined, use 'uname -s' to determine the OS name.
+#
+# uname on Windows gives "windows32", but most environments standardize
+# on "Windows_NT", so we'll make it consistent here.  When running
+# tests from Visual Studio, the environment variable isn't inherited
+# all the way down to the process spawned for make.
+#----------------------------------------------------------------------
+ifeq "$(OS)" ""
+	OS = $(shell uname -s)
+endif
+ifeq "$(OS)" "windows32"
+	OS = Windows_NT
+endif
+
+#----------------------------------------------------------------------
+# If ARCH is not defined, default to x86_64.
 #----------------------------------------------------------------------
 ifeq "$(ARCH)" ""
 ifeq "$(OS)" "Windows_NT"
@@ -41,10 +55,6 @@
 endif
 endif
 
-ifeq "$(OS)" ""
-	OS = $(shell uname -s)
-endif
-
 #----------------------------------------------------------------------
 # CC defaults to clang.
 #