Index: include/llvm/Support/YAMLTraits.h
===================================================================
--- include/llvm/Support/YAMLTraits.h
+++ include/llvm/Support/YAMLTraits.h
@@ -976,6 +976,10 @@
         void *Ctxt = nullptr,
         SourceMgr::DiagHandlerTy DiagHandler = nullptr,
         void *DiagHandlerCtxt = nullptr);
+  Input(MemoryBuffer &Input,
+        void *Ctxt = nullptr,
+        SourceMgr::DiagHandlerTy DiagHandler = nullptr,
+        void *DiagHandlerCtxt = nullptr);
   ~Input() override;
 
   // Check if there was an syntax or semantic error during parsing.
Index: lib/Support/YAMLTraits.cpp
===================================================================
--- lib/Support/YAMLTraits.cpp
+++ lib/Support/YAMLTraits.cpp
@@ -56,6 +56,19 @@
   DocIterator = Strm->begin();
 }
 
+Input::Input(MemoryBuffer &Input,
+             void *Ctxt,
+             SourceMgr::DiagHandlerTy DiagHandler,
+             void *DiagHandlerCtxt)
+  : IO(Ctxt),
+    Strm(new Stream(
+      MemoryBufferRef(Input.getBuffer(), Input.getBufferIdentifier()), SrcMgr)),
+    CurrentNode(nullptr) {
+  if (DiagHandler)
+    SrcMgr.setDiagHandler(DiagHandler, DiagHandlerCtxt);
+  DocIterator = Strm->begin();
+}
+
 Input::~Input() {
 }
 
Index: unittests/Support/YAMLIOTest.cpp
===================================================================
--- unittests/Support/YAMLIOTest.cpp
+++ unittests/Support/YAMLIOTest.cpp
@@ -233,6 +233,15 @@
   }
 }
 
+//
+// Test YAML filename handling.
+//
+TEST(YAMLIO, TestGivenFilename) {
+  // NOTE: Input doesn't expose enough information to retrieve the filename.
+  auto Buffer = llvm::MemoryBuffer::getMemBuffer("{ x: 42 }", "foo.yaml");
+  Input yin(*Buffer);
+}
+
 
 //===----------------------------------------------------------------------===//
 //  Test built-in types