diff --git a/llvm/unittests/Support/JSONTest.cpp b/llvm/unittests/Support/JSONTest.cpp
index 23645b3..14c11b1 100644
--- a/llvm/unittests/Support/JSONTest.cpp
+++ b/llvm/unittests/Support/JSONTest.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/JSON.h"
+#include "llvm/Support/raw_ostream.h"
 
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
@@ -383,6 +384,44 @@
       << "Wrong type for Optional<T> " << V;
 }
 
+TEST(JSONTest, Stream) {
+  auto StreamStuff = [](unsigned Indent) {
+    std::string S;
+    llvm::raw_string_ostream OS(S);
+    OStream J(OS, Indent);
+    J.object([&] {
+      J.attributeArray("foo", [&] {
+        J.value(nullptr);
+        J.value(42.5);
+        J.arrayBegin();
+        J.value(43);
+        J.arrayEnd();
+      });
+      J.attributeBegin("bar");
+      J.objectBegin();
+      J.objectEnd();
+      J.attributeEnd();
+      J.attribute("baz", "xyz");
+    });
+    return OS.str();
+  };
+
+  const char *Plain = R"({"foo":[null,42.5,[43]],"bar":{},"baz":"xyz"})";
+  EXPECT_EQ(Plain, StreamStuff(0));
+  const char *Pretty = R"({
+  "foo": [
+    null,
+    42.5,
+    [
+      43
+    ]
+  ],
+  "bar": {},
+  "baz": "xyz"
+})";
+  EXPECT_EQ(Pretty, StreamStuff(2));
+}
+
 } // namespace
 } // namespace json
 } // namespace llvm