diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index c2aff82..b01a3f6 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -620,7 +620,6 @@
       Diags.Report(diag::err_fe_error_reading) << InputFile;
       return false;
     }
-    SourceMgr.createMainFileID(File, Kind);
 
     // The natural SourceManager infrastructure can't currently handle named
     // pipes, but we would at least like to accept them for the main
@@ -632,8 +631,13 @@
         Diags.Report(diag::err_cannot_open_file) << InputFile << ec.message();
         return false;
       }
+
+      // Create a new virtual file that will have the correct size.
+      File = FileMgr.getVirtualFile(InputFile, MB->getBufferSize(), 0);
       SourceMgr.overrideFileContents(File, MB.take());
     }
+
+    SourceMgr.createMainFileID(File, Kind);
   } else {
     OwningPtr<llvm::MemoryBuffer> SB;
     if (llvm::MemoryBuffer::getSTDIN(SB)) {
diff --git a/test/Misc/dev-fd-fs.c b/test/Misc/dev-fd-fs.c
index fbc50fc..e35486e 100644
--- a/test/Misc/dev-fd-fs.c
+++ b/test/Misc/dev-fd-fs.c
@@ -1,8 +1,5 @@
 // Check that we can operate on files from /dev/fd.
 // REQUIRES: dev-fd-fs
-//
-// Currently, this only appears to work on Darwin's dev-fs.
-// REQUIRES: system-darwin
 
 
 // Check reading from named pipes. We cat the input here instead of redirecting