diff --git a/llvm/unittests/Support/TarWriterTest.cpp b/llvm/unittests/Support/TarWriterTest.cpp
index 6007e73..548efca 100644
--- a/llvm/unittests/Support/TarWriterTest.cpp
+++ b/llvm/unittests/Support/TarWriterTest.cpp
@@ -120,4 +120,60 @@
   StringRef Pax = StringRef((char *)(Buf.data() + 512), 512);
   EXPECT_TRUE(Pax.startswith("211 path=/" + std::string(200, 'x')));
 }
+
+TEST_F(TarWriterTest, SingleFile) {
+  SmallString<128> Path;
+  std::error_code EC =
+      sys::fs::createTemporaryFile("TarWriterTest", "tar", Path);
+  EXPECT_FALSE((bool)EC);
+
+  Expected<std::unique_ptr<TarWriter>> TarOrErr = TarWriter::create(Path, "");
+  EXPECT_TRUE((bool)TarOrErr);
+  std::unique_ptr<TarWriter> Tar = std::move(*TarOrErr);
+  Tar->append("FooPath", "foo");
+  Tar.reset();
+
+  uint64_t TarSize;
+  EC = sys::fs::file_size(Path, TarSize);
+  EXPECT_FALSE((bool)EC);
+  EXPECT_EQ(TarSize, 2048);
 }
+
+TEST_F(TarWriterTest, NoDuplicate) {
+  SmallString<128> Path;
+  std::error_code EC =
+      sys::fs::createTemporaryFile("TarWriterTest", "tar", Path);
+  EXPECT_FALSE((bool)EC);
+
+  Expected<std::unique_ptr<TarWriter>> TarOrErr = TarWriter::create(Path, "");
+  EXPECT_TRUE((bool)TarOrErr);
+  std::unique_ptr<TarWriter> Tar = std::move(*TarOrErr);
+  Tar->append("FooPath", "foo");
+  Tar->append("BarPath", "bar");
+  Tar.reset();
+
+  uint64_t TarSize;
+  EC = sys::fs::file_size(Path, TarSize);
+  EXPECT_FALSE((bool)EC);
+  EXPECT_EQ(TarSize, 3072);
+}
+
+TEST_F(TarWriterTest, Duplicate) {
+  SmallString<128> Path;
+  std::error_code EC =
+      sys::fs::createTemporaryFile("TarWriterTest", "tar", Path);
+  EXPECT_FALSE((bool)EC);
+
+  Expected<std::unique_ptr<TarWriter>> TarOrErr = TarWriter::create(Path, "");
+  EXPECT_TRUE((bool)TarOrErr);
+  std::unique_ptr<TarWriter> Tar = std::move(*TarOrErr);
+  Tar->append("FooPath", "foo");
+  Tar->append("FooPath", "bar");
+  Tar.reset();
+
+  uint64_t TarSize;
+  EC = sys::fs::file_size(Path, TarSize);
+  EXPECT_FALSE((bool)EC);
+  EXPECT_EQ(TarSize, 2048);
+}
+} // namespace