diff --git a/llvm/include/llvm/Support/CommandLine.h b/llvm/include/llvm/Support/CommandLine.h
--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -1366,7 +1366,7 @@
 
   // Make sure we initialize the value with the default constructor for the
   // type.
-  opt_storage() : Value(DataType()), Default(DataType()) {}
+  opt_storage() : Value(DataType()), Default() {}
 
   template <class T> void setValue(const T &V, bool initial = false) {
     Value = V;
diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -1972,4 +1972,60 @@
   EXPECT_EQ(0u, ExtraArgs.size());
 }
 
+TEST(CommandLineTest, DefaultValue) {
+  cl::ResetCommandLineParser();
+
+  StackOption<bool> BoolOption("bool-option");
+  StackOption<std::string> StrOption("str-option");
+  StackOption<bool> BoolInitOption("bool-init-option", cl::init(true));
+  StackOption<std::string> StrInitOption("str-init-option",
+                                         cl::init("str-default-value"));
+
+  const char *Args[] = {"prog"}; // no options
+
+  std::string Errs;
+  raw_string_ostream OS(Errs);
+  EXPECT_TRUE(cl::ParseCommandLineOptions(1, Args, StringRef(), &OS));
+  EXPECT_TRUE(OS.str().empty());
+
+  EXPECT_TRUE(!BoolOption);
+  EXPECT_FALSE(BoolOption.Default.hasValue());
+  EXPECT_EQ(0, BoolOption.getNumOccurrences());
+
+  EXPECT_EQ("", StrOption);
+  EXPECT_FALSE(StrOption.Default.hasValue());
+  EXPECT_EQ(0, StrOption.getNumOccurrences());
+
+  EXPECT_TRUE(BoolInitOption);
+  EXPECT_TRUE(BoolInitOption.Default.hasValue());
+  EXPECT_EQ(0, BoolInitOption.getNumOccurrences());
+
+  EXPECT_EQ("str-default-value", StrInitOption);
+  EXPECT_TRUE(StrInitOption.Default.hasValue());
+  EXPECT_EQ(0, StrInitOption.getNumOccurrences());
+
+  const char *Args2[] = {"prog", "-bool-option", "-str-option=str-value",
+                         "-bool-init-option=0",
+                         "-str-init-option=str-init-value"};
+
+  EXPECT_TRUE(cl::ParseCommandLineOptions(5, Args2, StringRef(), &OS));
+  EXPECT_TRUE(OS.str().empty());
+
+  EXPECT_TRUE(BoolOption);
+  EXPECT_FALSE(BoolOption.Default.hasValue());
+  EXPECT_EQ(1, BoolOption.getNumOccurrences());
+
+  EXPECT_EQ("str-value", StrOption);
+  EXPECT_FALSE(StrOption.Default.hasValue());
+  EXPECT_EQ(1, StrOption.getNumOccurrences());
+
+  EXPECT_FALSE(BoolInitOption);
+  EXPECT_TRUE(BoolInitOption.Default.hasValue());
+  EXPECT_EQ(1, BoolInitOption.getNumOccurrences());
+
+  EXPECT_EQ("str-init-value", StrInitOption);
+  EXPECT_TRUE(StrInitOption.Default.hasValue());
+  EXPECT_EQ(1, StrInitOption.getNumOccurrences());
+}
+
 } // anonymous namespace