diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index dc1afcb..0d4f303 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -4662,7 +4662,8 @@
     llvm::MemoryBuffer *ToBuf
       = llvm::MemoryBuffer::getMemBufferCopy(FromBuf->getBuffer(),
                                              FromBuf->getBufferIdentifier());
-    ToID = ToSM.createFileIDForMemBuffer(ToBuf);
+    ToID = ToSM.createFileIDForMemBuffer(ToBuf,
+                                    FromSLoc.getFile().getFileCharacteristic());
   }
   
   
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index 9e7b630..22a74fc 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -600,10 +600,18 @@
                                                FileManager &FileMgr,
                                                SourceManager &SourceMgr,
                                                const FrontendOptions &Opts) {
-  StringRef InputFile = Input.getFile();
   SrcMgr::CharacteristicKind
     Kind = Input.isSystem() ? SrcMgr::C_System : SrcMgr::C_User;
 
+  if (Input.isBuffer()) {
+    SourceMgr.createMainFileIDForMemBuffer(Input.getBuffer(), Kind);
+    assert(!SourceMgr.getMainFileID().isInvalid() &&
+           "Couldn't establish MainFileID!");
+    return true;
+  }
+
+  StringRef InputFile = Input.getFile();
+
   // Figure out where to get and map in the main file.
   if (InputFile != "-") {
     const FileEntry *File = FileMgr.getFile(InputFile);
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 0f3e553..deba302 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -961,6 +961,8 @@
   case SM_SLOC_BUFFER_ENTRY: {
     const char *Name = BlobStart;
     unsigned Offset = Record[0];
+    SrcMgr::CharacteristicKind
+      FileCharacter = (SrcMgr::CharacteristicKind)Record[2];
     SourceLocation IncludeLoc = ReadSourceLocation(*F, Record[1]);
     unsigned Code = SLocEntryCursor.ReadCode();
     Record.clear();
@@ -975,8 +977,8 @@
     llvm::MemoryBuffer *Buffer
       = llvm::MemoryBuffer::getMemBuffer(StringRef(BlobStart, BlobLen - 1),
                                          Name);
-    SourceMgr.createFileIDForMemBuffer(Buffer, ID, BaseOffset + Offset,
-                                       IncludeLoc);
+    SourceMgr.createFileIDForMemBuffer(Buffer, FileCharacter, ID,
+                                       BaseOffset + Offset, IncludeLoc);
     break;
   }