diff --git a/unittests/Tooling/JsonCompileCommandLineDatabaseTest.cpp b/unittests/Tooling/JsonCompileCommandLineDatabaseTest.cpp
new file mode 100644
index 0000000..d875293
--- /dev/null
+++ b/unittests/Tooling/JsonCompileCommandLineDatabaseTest.cpp
@@ -0,0 +1,232 @@
+//===- unittest/Tooling/JsonCompileCommandLineDatabaseTest ----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../../lib/Tooling/JsonCompileCommandLineDatabase.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tooling {
+
+TEST(UnescapeJsonCommandLine, ReturnsEmptyArrayOnEmptyString) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine("");
+  EXPECT_TRUE(Result.empty());
+}
+
+TEST(UnescapeJsonCommandLine, SplitsOnSpaces) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine("a b c");
+  ASSERT_EQ(3ul, Result.size());
+  EXPECT_EQ("a", Result[0]);
+  EXPECT_EQ("b", Result[1]);
+  EXPECT_EQ("c", Result[2]);
+}
+
+TEST(UnescapeJsonCommandLine, MungesMultipleSpaces) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine("   a   b   ");
+  ASSERT_EQ(2ul, Result.size());
+  EXPECT_EQ("a", Result[0]);
+  EXPECT_EQ("b", Result[1]);
+}
+
+TEST(UnescapeJsonCommandLine, UnescapesBackslashCharacters) {
+  std::vector<std::string> Backslash = UnescapeJsonCommandLine("a\\\\\\\\");
+  ASSERT_EQ(1ul, Backslash.size());
+  EXPECT_EQ("a\\", Backslash[0]);
+  std::vector<std::string> Quote = UnescapeJsonCommandLine("a\\\\\\\"");
+  ASSERT_EQ(1ul, Quote.size());
+  EXPECT_EQ("a\"", Quote[0]);
+}
+
+TEST(UnescapeJsonCommandLine, DoesNotMungeSpacesBetweenQuotes) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine("\\\"  a  b  \\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_EQ("  a  b  ", Result[0]);
+}
+
+TEST(UnescapeJsonCommandLine, AllowsMultipleQuotedArguments) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine(
+      "  \\\" a \\\"  \\\" b \\\"  ");
+  ASSERT_EQ(2ul, Result.size());
+  EXPECT_EQ(" a ", Result[0]);
+  EXPECT_EQ(" b ", Result[1]);
+}
+
+TEST(UnescapeJsonCommandLine, AllowsEmptyArgumentsInQuotes) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine(
+      "\\\"\\\"\\\"\\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_TRUE(Result[0].empty()) << Result[0];
+}
+
+TEST(UnescapeJsonCommandLine, ParsesEscapedQuotesInQuotedStrings) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine(
+      "\\\"\\\\\\\"\\\"");
+  ASSERT_EQ(1ul, Result.size());
+  EXPECT_EQ("\"", Result[0]);
+}
+
+TEST(UnescapeJsonCommandLine, ParsesMultipleArgumentsWithEscapedCharacters) {
+  std::vector<std::string> Result = UnescapeJsonCommandLine(
+      "  \\\\\\\"  \\\"a \\\\\\\" b \\\"     \\\"and\\\\\\\\c\\\"   \\\\\\\"");
+  ASSERT_EQ(4ul, Result.size());
+  EXPECT_EQ("\"", Result[0]);
+  EXPECT_EQ("a \" b ", Result[1]);
+  EXPECT_EQ("and\\c", Result[2]);
+  EXPECT_EQ("\"", Result[3]);
+}
+
+TEST(UnescapeJsonCommandLine, ParsesStringsWithoutSpacesIntoSingleArgument) {
+  std::vector<std::string> QuotedNoSpaces = UnescapeJsonCommandLine(
+      "\\\"a\\\"\\\"b\\\"");
+  ASSERT_EQ(1ul, QuotedNoSpaces.size());
+  EXPECT_EQ("ab", QuotedNoSpaces[0]);
+
+  std::vector<std::string> MixedNoSpaces = UnescapeJsonCommandLine(
+      "\\\"a\\\"bcd\\\"ef\\\"\\\"\\\"\\\"g\\\"");
+  ASSERT_EQ(1ul, MixedNoSpaces.size());
+  EXPECT_EQ("abcdefg", MixedNoSpaces[0]);
+}
+
+TEST(JsonCompileCommandLineParser, FailsOnEmptyString) {
+  JsonCompileCommandLineParser Parser("", NULL);
+  EXPECT_FALSE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, DoesNotReadAfterInput) {
+  JsonCompileCommandLineParser Parser(llvm::StringRef(NULL, 0), NULL);
+  EXPECT_FALSE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesEmptyArray) {
+  JsonCompileCommandLineParser Parser("[]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsIfNotClosingArray) {
+  JsonCompileCommandLineParser JustOpening("[", NULL);
+  EXPECT_FALSE(JustOpening.Parse()) << JustOpening.GetErrorMessage();
+  JsonCompileCommandLineParser WithSpaces("  [  ", NULL);
+  EXPECT_FALSE(WithSpaces.Parse()) << WithSpaces.GetErrorMessage();
+  JsonCompileCommandLineParser WithGarbage("  [x", NULL);
+  EXPECT_FALSE(WithGarbage.Parse()) << WithGarbage.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesEmptyArrayWithWhitespace) {
+  JsonCompileCommandLineParser Spaces("   [   ]   ", NULL);
+  EXPECT_TRUE(Spaces.Parse()) << Spaces.GetErrorMessage();
+  JsonCompileCommandLineParser AllWhites("\t\r\n[\t\n \t\r ]\t\r \n\n", NULL);
+  EXPECT_TRUE(AllWhites.Parse()) << AllWhites.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsIfNotStartingArray) {
+  JsonCompileCommandLineParser ObjectStart("{", NULL);
+  EXPECT_FALSE(ObjectStart.Parse()) << ObjectStart.GetErrorMessage();
+  // We don't implement a full JSON parser, and thus parse only a subset
+  // of valid JSON.
+  JsonCompileCommandLineParser Object("{}", NULL);
+  EXPECT_FALSE(Object.Parse()) << Object.GetErrorMessage();
+  JsonCompileCommandLineParser Character("x", NULL);
+  EXPECT_FALSE(Character.Parse()) << Character.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesEmptyObject) {
+  JsonCompileCommandLineParser Parser("[{}]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesObject) {
+  JsonCompileCommandLineParser Parser("[{\"a\":\"/b\"}]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesMultipleKeyValuePairsInObject) {
+  JsonCompileCommandLineParser Parser(
+      "[{\"a\":\"/b\",\"c\":\"d\",\"e\":\"f\"}]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsIfNotClosingObject) {
+  JsonCompileCommandLineParser MissingCloseOnEmpty("[{]", NULL);
+  EXPECT_FALSE(MissingCloseOnEmpty.Parse())
+      << MissingCloseOnEmpty.GetErrorMessage();
+  JsonCompileCommandLineParser MissingCloseAfterPair("[{\"a\":\"b\"]", NULL);
+  EXPECT_FALSE(MissingCloseAfterPair.Parse())
+      << MissingCloseAfterPair.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsIfMissingColon) {
+  JsonCompileCommandLineParser StringString("[{\"a\"\"/b\"}]", NULL);
+  EXPECT_FALSE(StringString.Parse()) << StringString.GetErrorMessage();
+  JsonCompileCommandLineParser StringSpaceString("[{\"a\" \"b\"}]", NULL);
+  EXPECT_FALSE(StringSpaceString.Parse())
+      << StringSpaceString.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsOnMissingQuote) {
+  JsonCompileCommandLineParser OpenQuote("[{a\":\"b\"}]", NULL);
+  EXPECT_FALSE(OpenQuote.Parse()) << OpenQuote.GetErrorMessage();
+  JsonCompileCommandLineParser CloseQuote("[{\"a\":\"b}]", NULL);
+  EXPECT_FALSE(CloseQuote.Parse()) << CloseQuote.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesEscapedQuotes) {
+  JsonCompileCommandLineParser Parser(
+      "[{\"a\":\"\\\"b\\\"  \\\" \\\"\"}]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesEmptyString) {
+  JsonCompileCommandLineParser Parser("[{\"a\":\"\"}]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsOnMissingString) {
+  JsonCompileCommandLineParser MissingValue("[{\"a\":}]", NULL);
+  EXPECT_FALSE(MissingValue.Parse()) << MissingValue.GetErrorMessage();
+  JsonCompileCommandLineParser MissingKey("[{:\"b\"}]", NULL);
+  EXPECT_FALSE(MissingKey.Parse()) << MissingKey.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesMultipleObjects) {
+  JsonCompileCommandLineParser Parser(
+      "["
+      " { \"a\" : \"b\" },"
+      " { \"a\" : \"b\" },"
+      " { \"a\" : \"b\" }"
+      "]", NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsOnMissingComma) {
+  JsonCompileCommandLineParser Parser(
+      "["
+      " { \"a\" : \"b\" }"
+      " { \"a\" : \"b\" }"
+      "]", NULL);
+  EXPECT_FALSE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, FailsOnSuperfluousComma) {
+  JsonCompileCommandLineParser Parser(
+      "[ { \"a\" : \"b\" }, ]", NULL);
+  EXPECT_FALSE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+TEST(JsonCompileCommandLineParser, ParsesSpacesInBetweenTokens) {
+  JsonCompileCommandLineParser Parser(
+      " \t \n\n \r [ \t \n\n \r"
+      " \t \n\n \r { \t \n\n \r\"a\"\t \n\n \r :"
+      " \t \n\n \r \"b\"\t \n\n \r } \t \n\n \r,\t \n\n \r"
+      " \t \n\n \r { \t \n\n \r\"a\"\t \n\n \r :"
+      " \t \n\n \r \"b\"\t \n\n \r } \t \n\n \r]\t \n\n \r",
+      NULL);
+  EXPECT_TRUE(Parser.Parse()) << Parser.GetErrorMessage();
+}
+
+} // end namespace tooling
+} // end namespace clang