diff --git a/llvm/lib/Support/CommandLine.cpp b/llvm/lib/Support/CommandLine.cpp
index 4c9250236a3b54..2f749bf7a6989e 100644
--- a/llvm/lib/Support/CommandLine.cpp
+++ b/llvm/lib/Support/CommandLine.cpp
@@ -1008,7 +1008,7 @@ tokenizeWindowsCommandLineImpl(StringRef Src, StringSaver &Saver,
     }
   }
 
-  if (State == UNQUOTED)
+  if (State != INIT)
     AddToken(Saver.save(Token.str()));
 }
 
diff --git a/llvm/lib/Support/Windows/Process.inc b/llvm/lib/Support/Windows/Process.inc
index dfaab1613de185..b1af298d9e83ea 100644
--- a/llvm/lib/Support/Windows/Process.inc
+++ b/llvm/lib/Support/Windows/Process.inc
@@ -255,6 +255,9 @@ windows::GetCommandLineArguments(SmallVectorImpl<const char *> &Args,
       return EC;
   }
 
+  if (Args.size() == 0)
+    return std::make_error_code(std::errc::invalid_argument);
+
   SmallVector<char, MAX_PATH> Arg0(Args[0], Args[0] + strlen(Args[0]));
   SmallVector<char, MAX_PATH> Filename;
   sys::path::remove_filename(Arg0);
diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
index dd02d920126520..7f751e5e101bd3 100644
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -237,12 +237,24 @@ TEST(CommandLineTest, TokenizeWindowsCommandLine2) {
 }
 
 TEST(CommandLineTest, TokenizeWindowsCommandLineQuotedLastArgument) {
+  // Whitespace at the end of the command line doesn't cause an empty last word
+  const char Input0[] = R"(a b c d )";
+  const char *const Output0[] = {"a", "b", "c", "d"};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input0, Output0);
+
+  // But an explicit "" does
   const char Input1[] = R"(a b c d "")";
   const char *const Output1[] = {"a", "b", "c", "d", ""};
   testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input1, Output1);
+
+  // An unterminated quoted string is also emitted as an argument word, empty
+  // or not
   const char Input2[] = R"(a b c d ")";
-  const char *const Output2[] = {"a", "b", "c", "d"};
+  const char *const Output2[] = {"a", "b", "c", "d", ""};
   testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input2, Output2);
+  const char Input3[] = R"(a b c d "text)";
+  const char *const Output3[] = {"a", "b", "c", "d", "text"};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input3, Output3);
 }
 
 TEST(CommandLineTest, TokenizeAndMarkEOLs) {