diff --git a/unittests/Tooling/CompilationDatabaseTest.cpp b/unittests/Tooling/CompilationDatabaseTest.cpp
new file mode 100644
index 0000000..9747de2
--- /dev/null
+++ b/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -0,0 +1,223 @@
+//===- unittest/Tooling/CompilationDatabaseTest.cpp -----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclGroup.h"
+#include "clang/Frontend/FrontendAction.h"
+#include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/Tooling.h"
+#include "gtest/gtest.h"
+
+namespace clang {
+namespace tooling {
+
+static CompileCommand findCompileArgsInJsonDatabase(StringRef FileName,
+                                                    StringRef JSONDatabase,
+                                                    std::string &ErrorMessage) {
+  llvm::OwningPtr<CompilationDatabase> Database(
+      JSONCompilationDatabase::loadFromBuffer(JSONDatabase, ErrorMessage));
+  if (!Database)
+    return CompileCommand();
+  std::vector<CompileCommand> Commands = Database->getCompileCommands(FileName);
+  EXPECT_LE(Commands.size(), 1u);
+  if (Commands.empty())
+    return CompileCommand();
+  return Commands[0];
+}
+
+TEST(findCompileArgsInJsonDatabase, FindsNothingIfEmpty) {
+  std::string ErrorMessage;
+  CompileCommand NotFound = findCompileArgsInJsonDatabase(
+    "a-file.cpp", "", ErrorMessage);
+  EXPECT_TRUE(NotFound.CommandLine.empty()) << ErrorMessage;
+  EXPECT_TRUE(NotFound.Directory.empty()) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsSingleEntry) {
+  StringRef Directory("/some/directory");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("/path/to/compiler and some arguments");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_EQ(Directory, FoundCommand.Directory) << ErrorMessage;
+  ASSERT_EQ(4u, FoundCommand.CommandLine.size()) << ErrorMessage;
+  EXPECT_EQ("/path/to/compiler", FoundCommand.CommandLine[0]) << ErrorMessage;
+  EXPECT_EQ("and", FoundCommand.CommandLine[1]) << ErrorMessage;
+  EXPECT_EQ("some", FoundCommand.CommandLine[2]) << ErrorMessage;
+  EXPECT_EQ("arguments", FoundCommand.CommandLine[3]) << ErrorMessage;
+
+  CompileCommand NotFound = findCompileArgsInJsonDatabase(
+    "a-file.cpp",
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_TRUE(NotFound.Directory.empty()) << ErrorMessage;
+  EXPECT_TRUE(NotFound.CommandLine.empty()) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsCompileCommandLinesWithSpaces) {
+  StringRef Directory("/some/directory");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("\\\"/path to compiler\\\" \\\"and an argument\\\"");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  ASSERT_EQ(2u, FoundCommand.CommandLine.size());
+  EXPECT_EQ("/path to compiler", FoundCommand.CommandLine[0]) << ErrorMessage;
+  EXPECT_EQ("and an argument", FoundCommand.CommandLine[1]) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, ReadsDirectoryWithSpaces) {
+  StringRef Directory("/some directory / with spaces");
+  StringRef FileName("/path/to/a-file.cpp");
+  StringRef Command("a command");
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    FileName,
+    ("[{\"directory\":\"" + Directory + "\"," +
+       "\"command\":\"" + Command + "\","
+       "\"file\":\"" + FileName + "\"}]").str(),
+    ErrorMessage);
+  EXPECT_EQ(Directory, FoundCommand.Directory) << ErrorMessage;
+}
+
+TEST(findCompileArgsInJsonDatabase, FindsEntry) {
+  StringRef Directory("directory");
+  StringRef FileName("file");
+  StringRef Command("command");
+  std::string JsonDatabase = "[";
+  for (int I = 0; I < 10; ++I) {
+    if (I > 0) JsonDatabase += ",";
+    JsonDatabase +=
+      ("{\"directory\":\"" + Directory + Twine(I) + "\"," +
+        "\"command\":\"" + Command + Twine(I) + "\","
+        "\"file\":\"" + FileName + Twine(I) + "\"}").str();
+  }
+  JsonDatabase += "]";
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    "file4", JsonDatabase, ErrorMessage);
+  EXPECT_EQ("directory4", FoundCommand.Directory) << ErrorMessage;
+  ASSERT_EQ(1u, FoundCommand.CommandLine.size()) << ErrorMessage;
+  EXPECT_EQ("command4", FoundCommand.CommandLine[0]) << ErrorMessage;
+}
+
+static std::vector<std::string> unescapeJsonCommandLine(StringRef Command) {
+  std::string JsonDatabase =
+    ("[{\"directory\":\"\", \"file\":\"test\", \"command\": \"" +
+     Command + "\"}]").str();
+  std::string ErrorMessage;
+  CompileCommand FoundCommand = findCompileArgsInJsonDatabase(
+    "test", JsonDatabase, ErrorMessage);
+  EXPECT_TRUE(ErrorMessage.empty()) << ErrorMessage;
+  return FoundCommand.CommandLine;
+}
+
+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(unescapeJsonCommandLine, ParsesQuotedStringWithoutClosingQuote) {
+  std::vector<std::string> Unclosed = unescapeJsonCommandLine("\\\"abc");
+  ASSERT_EQ(1ul, Unclosed.size());
+  EXPECT_EQ("abc", Unclosed[0]);
+
+  std::vector<std::string> Empty = unescapeJsonCommandLine("\\\"");
+  ASSERT_EQ(1ul, Empty.size());
+  EXPECT_EQ("", Empty[0]);
+}
+
+} // end namespace tooling
+} // end namespace clang