Index: cfe/trunk/include/clang/Serialization/ASTReader.h
===================================================================
--- cfe/trunk/include/clang/Serialization/ASTReader.h
+++ cfe/trunk/include/clang/Serialization/ASTReader.h
@@ -867,9 +867,6 @@
   SmallVector<ImportedSubmodule, 2> ImportedModules;
   //@}
 
-  /// \brief The directory that the PCH we are reading is stored in.
-  std::string CurrentDir;
-
   /// \brief The system include root to be used when loading the
   /// precompiled header.
   std::string isysroot;
Index: cfe/trunk/lib/Serialization/ASTReader.cpp
===================================================================
--- cfe/trunk/lib/Serialization/ASTReader.cpp
+++ cfe/trunk/lib/Serialization/ASTReader.cpp
@@ -2060,14 +2060,12 @@
   StringRef Filename = FI.Filename;
 
   const FileEntry *File = FileMgr.getFile(Filename, /*OpenFile=*/false);
-
   // If we didn't find the file, resolve it relative to the
   // original directory from which this AST file was created.
-  if (File == nullptr && !F.OriginalDir.empty() && !CurrentDir.empty() &&
-      F.OriginalDir != CurrentDir) {
-    std::string Resolved = resolveFileRelativeToOriginalDir(Filename,
-                                                            F.OriginalDir,
-                                                            CurrentDir);
+  if (File == nullptr && !F.OriginalDir.empty() && !F.BaseDirectory.empty() &&
+      F.OriginalDir != F.BaseDirectory) {
+    std::string Resolved = resolveFileRelativeToOriginalDir(
+        Filename, F.OriginalDir, F.BaseDirectory);
     if (!Resolved.empty())
       File = FileMgr.getFile(Resolved);
   }
@@ -4065,13 +4063,6 @@
 
   assert(M && "Missing module file");
 
-  // FIXME: This seems rather a hack. Should CurrentDir be part of the
-  // module?
-  if (FileName != "-") {
-    CurrentDir = llvm::sys::path::parent_path(FileName);
-    if (CurrentDir.empty()) CurrentDir = ".";
-  }
-
   ModuleFile &F = *M;
   BitstreamCursor &Stream = F.Stream;
   Stream = BitstreamCursor(PCHContainerRdr.ExtractPCH(*F.Buffer));
Index: cfe/trunk/test/Modules/path-resolution.modulemap
===================================================================
--- cfe/trunk/test/Modules/path-resolution.modulemap
+++ cfe/trunk/test/Modules/path-resolution.modulemap
@@ -0,0 +1,70 @@
+// RUN: rm -rf %t
+//
+// First, create two modules a and b, with a dependency b -> a, both within
+// the same directory p1.
+//
+// RUN: mkdir -p %t/p1
+// RUN: cd %t/p1
+//
+// RUN: grep "<AM>" %s > %t/p1/a.modulemap
+// RUN: %clang_cc1 -x c++ -fmodules -emit-module -fmodule-map-file-home-is-cwd \
+// RUN:   -fmodules-embed-all-files -fmodules-local-submodule-visibility \
+// RUN:   -fmodule-name="a" -o a.pcm a.modulemap
+//
+// RUN: grep "<BM>" %s > %t/p1/b.modulemap
+// RUN: %clang_cc1 -x c++ -fmodules -emit-module -fmodule-map-file-home-is-cwd \
+// RUN:   -fmodules-embed-all-files -fmodules-local-submodule-visibility \
+// RUN:   -fmodule-name="b" -o b.pcm b.modulemap
+//
+// Next, move the whole tree p1 -> p2.
+//
+// RUN: cd %t
+// RUN: mv %t/p1 %t/p2
+// RUN: cd %t/p2
+//
+// Compile a new module c in the newly generated tree that depends on b; c.pcm
+// has to be within a subdirectory so a.modulemap will be one step up (../) from
+// c.pcm.
+//
+// RUN: mkdir %t/p2/c
+// RUN: grep "<CM>" %s > %t/p2/c/c.modulemap
+// RUN: grep "<CH>" %s > %t/p2/c/c.h
+// RUN: %clang_cc1 -x c++ -fmodules -emit-module -fmodule-map-file-home-is-cwd \
+// RUN:   -fmodules-embed-all-files -fmodules-local-submodule-visibility \
+// RUN:   -fmodule-name="c" -fmodule-file=b.pcm -o c/c.pcm c/c.modulemap
+//
+// Delete a.modulemap from its original location, and instead inject a different
+// (unrelated) a.modulemap in the path p2/p2.
+//
+// RUN: rm %t/p2/a.modulemap
+// RUN: mkdir -p %t/p2/p2
+// RUN: touch %t/p2/p2/a.modulemap
+//
+// Now compile a file c.cpp that uses c.h and the module c; it is important
+// to first load b.pcm and a.pcm before c.pcm on the command line to trigger
+// the right order of module loading. This used to trigger clang to find the
+// p2/p2/a.modulemap via the path c/../p2/a.modulemap, which is not the correct
+// relative path from c.
+//
+// RUN: grep "<CC>" %s > %t/p2/c/c.cpp
+// RUN: %clang_cc1 -I. -x c++ -fmodules \
+// RUN:     -fmodule-file=b.pcm -fmodule-file=a.pcm -fmodule-file=c/c.pcm  \
+// RUN:     -o c/c.o -emit-obj c/c.cpp
+
+module "a" {                // <AM>
+}                           // <AM>
+
+module "b" {                // <BM>
+  use "a"                   // <BM>
+}                           // <BM>
+
+module "c" {                // <CM>
+  header "c/c.h"            // <CM>
+  use "a"                   // <CM>
+  use "b"                   // <CM>
+}                           // <CM>
+
+inline void c() {}          // <CH>
+
+#include "c/c.h"            // <CC>
+void foo() { c(); }         // <CC>