diff --git a/llvm/unittests/Support/SymbolRemappingReaderTest.cpp b/llvm/unittests/Support/SymbolRemappingReaderTest.cpp
new file mode 100644
index 0000000..717df62
--- /dev/null
+++ b/llvm/unittests/Support/SymbolRemappingReaderTest.cpp
@@ -0,0 +1,96 @@
+//===- unittests/Support/SymbolRemappingReaderTest.cpp --------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/SymbolRemappingReader.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+namespace {
+class SymbolRemappingReaderTest : public testing::Test {
+public:
+  std::unique_ptr<MemoryBuffer> Buffer;
+  SymbolRemappingReader Reader;
+
+  std::string readWithErrors(StringRef Text, StringRef BufferName) {
+    Buffer = MemoryBuffer::getMemBuffer(Text, BufferName);
+    Error E = Reader.read(*Buffer);
+    EXPECT_TRUE((bool)E);
+    return toString(std::move(E));
+  }
+
+  void read(StringRef Text, StringRef BufferName) {
+    Buffer = MemoryBuffer::getMemBuffer(Text, BufferName);
+    Error E = Reader.read(*Buffer);
+    EXPECT_FALSE((bool)E);
+  }
+};
+} // unnamed namespace
+
+TEST_F(SymbolRemappingReaderTest, ParseErrors) {
+  EXPECT_EQ(readWithErrors("error", "foo.map"),
+            "foo.map:1: Expected 'kind mangled_name mangled_name', "
+            "found 'error'");
+
+  EXPECT_EQ(readWithErrors("error m1 m2", "foo.map"),
+            "foo.map:1: Invalid kind, expected 'name', 'type', or 'encoding', "
+            "found 'error'");
+}
+
+TEST_F(SymbolRemappingReaderTest, DemanglingErrors) {
+  EXPECT_EQ(readWithErrors("type i banana", "foo.map"),
+            "foo.map:1: Could not demangle 'banana' as a <type>; "
+            "invalid mangling?");
+  EXPECT_EQ(readWithErrors("name i 1X", "foo.map"),
+            "foo.map:1: Could not demangle 'i' as a <name>; "
+            "invalid mangling?");
+  EXPECT_EQ(readWithErrors("name 1X 1fv", "foo.map"),
+            "foo.map:1: Could not demangle '1fv' as a <name>; "
+            "invalid mangling?");
+  EXPECT_EQ(readWithErrors("encoding 1fv 1f1gE", "foo.map"),
+            "foo.map:1: Could not demangle '1f1gE' as a <encoding>; "
+            "invalid mangling?");
+}
+
+TEST_F(SymbolRemappingReaderTest, BadMappingOrder) {
+  StringRef Map = R"(
+    # N::foo == M::bar
+    name N1N3fooE N1M3barE
+
+    # N:: == M::
+    name 1N 1M
+  )";
+  EXPECT_EQ(readWithErrors(Map, "foo.map"),
+            "foo.map:6: Manglings '1N' and '1M' have both been used in prior "
+            "remappings. Move this remapping earlier in the file.");
+}
+
+TEST_F(SymbolRemappingReaderTest, RemappingsAdded) {
+  StringRef Map = R"(
+    # A::foo == B::bar
+    name N1A3fooE N1B3barE
+
+    # int == long
+    type i l
+
+    # void f<int>() = void g<int>()
+    encoding 1fIiEvv 1gIiEvv
+  )";
+
+  read(Map, "foo.map");
+  auto Key = Reader.insert("_ZN1B3bar3bazIiEEvv");
+  EXPECT_NE(Key, SymbolRemappingReader::Key());
+  EXPECT_EQ(Key, Reader.lookup("_ZN1A3foo3bazIlEEvv"));
+  EXPECT_NE(Key, Reader.lookup("_ZN1C3foo3bazIlEEvv"));
+
+  Key = Reader.insert("_Z1fIiEvv");
+  EXPECT_NE(Key, SymbolRemappingReader::Key());
+  EXPECT_EQ(Key, Reader.lookup("_Z1gIlEvv"));
+}