diff --git a/unittests/Basic/Makefile b/unittests/Basic/Makefile
index 4bac50c..82de790 100644
--- a/unittests/Basic/Makefile
+++ b/unittests/Basic/Makefile
@@ -10,6 +10,6 @@
 CLANG_LEVEL = ../..
 TESTNAME = Basic
 LINK_COMPONENTS := support mc
-USEDLIBS = clangBasic.a
+USEDLIBS = clangLex.a clangBasic.a
 
 include $(CLANG_LEVEL)/unittests/Makefile
diff --git a/unittests/Basic/SourceManagerTest.cpp b/unittests/Basic/SourceManagerTest.cpp
new file mode 100644
index 0000000..caab441
--- /dev/null
+++ b/unittests/Basic/SourceManagerTest.cpp
@@ -0,0 +1,108 @@
+//===- unittests/Basic/SourceManagerTest.cpp ------ SourceManager tests ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/TargetOptions.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Lex/ModuleLoader.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/Preprocessor.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace clang;
+
+namespace {
+
+// The test fixture.
+class SourceManagerTest : public ::testing::Test {
+protected:
+  SourceManagerTest()
+    : FileMgr(FileMgrOpts),
+      DiagID(new DiagnosticIDs()),
+      Diags(DiagID, new IgnoringDiagConsumer()),
+      SourceMgr(Diags, FileMgr) {
+    TargetOpts.Triple = "x86_64-apple-darwin11.1.0";
+    Target = TargetInfo::CreateTargetInfo(Diags, TargetOpts);
+  }
+
+  FileSystemOptions FileMgrOpts;
+  FileManager FileMgr;
+  llvm::IntrusiveRefCntPtr<DiagnosticIDs> DiagID;
+  DiagnosticsEngine Diags;
+  SourceManager SourceMgr;
+  LangOptions LangOpts;
+  TargetOptions TargetOpts;
+  llvm::IntrusiveRefCntPtr<TargetInfo> Target;
+};
+
+class VoidModuleLoader : public ModuleLoader {
+  virtual Module *loadModule(SourceLocation ImportLoc, ModuleIdPath Path,
+                             Module::NameVisibilityKind Visibility,
+                             bool IsInclusionDirective) {
+    return 0;
+  }
+};
+
+TEST_F(SourceManagerTest, isBeforeInTranslationUnit) {
+  const char *source =
+    "#define M(x) [x]\n"
+    "M(foo)";
+  MemoryBuffer *buf = MemoryBuffer::getMemBuffer(source);
+  FileID mainFileID = SourceMgr.createMainFileIDForMemBuffer(buf);
+
+  VoidModuleLoader ModLoader;
+  HeaderSearch HeaderInfo(FileMgr, Diags);
+  Preprocessor PP(Diags, LangOpts,
+                  Target.getPtr(),
+                  SourceMgr, HeaderInfo, ModLoader,
+                  /*IILookup =*/ 0,
+                  /*OwnsHeaderSearch =*/false,
+                  /*DelayInitialization =*/ false);
+  PP.EnterMainSourceFile();
+
+  std::vector<Token> toks;
+  while (1) {
+    Token tok;
+    PP.Lex(tok);
+    if (tok.is(tok::eof))
+      break;
+    toks.push_back(tok);
+  }
+
+  // Make sure we got the tokens that we expected.
+  ASSERT_EQ(3U, toks.size());
+  ASSERT_EQ(tok::l_square, toks[0].getKind());
+  ASSERT_EQ(tok::identifier, toks[1].getKind());
+  ASSERT_EQ(tok::r_square, toks[2].getKind());
+  
+  SourceLocation lsqrLoc = toks[0].getLocation();
+  SourceLocation idLoc = toks[1].getLocation();
+  SourceLocation rsqrLoc = toks[2].getLocation();
+  
+  SourceLocation macroExpStartLoc = SourceMgr.translateLineCol(mainFileID, 2, 1);
+  SourceLocation macroExpEndLoc = SourceMgr.translateLineCol(mainFileID, 2, 6);
+  ASSERT_TRUE(macroExpStartLoc.isFileID());
+  ASSERT_TRUE(macroExpEndLoc.isFileID());
+
+  llvm::SmallString<32> str;
+  ASSERT_EQ("M", PP.getSpelling(macroExpStartLoc, str));
+  ASSERT_EQ(")", PP.getSpelling(macroExpEndLoc, str));
+
+  EXPECT_TRUE(SourceMgr.isBeforeInTranslationUnit(lsqrLoc, idLoc));
+  EXPECT_TRUE(SourceMgr.isBeforeInTranslationUnit(idLoc, rsqrLoc));
+  EXPECT_TRUE(SourceMgr.isBeforeInTranslationUnit(macroExpStartLoc, idLoc));
+  EXPECT_TRUE(SourceMgr.isBeforeInTranslationUnit(idLoc, macroExpEndLoc));
+}
+
+} // anonymous namespace