Index: llvm/lib/Support/CommandLine.cpp
===================================================================
--- llvm/lib/Support/CommandLine.cpp
+++ llvm/lib/Support/CommandLine.cpp
@@ -919,6 +919,14 @@
     Token.push_back('"');
     return I;
   }
+
+  bool FollowedBySpace = (I != E && Src[I] == ' ');
+  if (FollowedBySpace && (BackslashCount % 2 == 1)) {
+    Token.append(BackslashCount - 1, '\\');
+    Token.append(1, ' ');
+    return I;
+  }
+
   Token.append(BackslashCount, '\\');
   return I - 1;
 }
Index: llvm/unittests/Support/CommandLineTest.cpp
===================================================================
--- llvm/unittests/Support/CommandLineTest.cpp
+++ llvm/unittests/Support/CommandLineTest.cpp
@@ -239,6 +239,14 @@
                            array_lengthof(Output));
 }
 
+TEST(CommandLineTest, TokenizeWindowsCommandLine3) {
+  const char Input[] = "-o D:/work\\ folder\\ foo -o D:/work\\\\ folder";
+  const char *const Output[] = {"-o", "D:/work folder foo", "-o", "D:/work\\\\",
+                                "folder"};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input, Output,
+                           array_lengthof(Output));
+}
+
 TEST(CommandLineTest, TokenizeWindowsCommandLineQuotedLastArgument) {
   const char Input1[] = R"(a b c d "")";
   const char *const Output1[] = {"a", "b", "c", "d", ""};