Index: lib/BinaryFormat/MsgPackDocumentYAML.cpp
===================================================================
--- lib/BinaryFormat/MsgPackDocumentYAML.cpp
+++ lib/BinaryFormat/MsgPackDocumentYAML.cpp
@@ -61,7 +61,7 @@
     llvm_unreachable("not scalar");
     break;
   }
-  return S;
+  return OS.str();
 }
 
 /// Convert the StringRef and use it to set this DocNode (assuming scalar). If
Index: lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
===================================================================
--- lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
+++ lib/Target/AMDGPU/SIMachineFunctionInfo.cpp
@@ -325,6 +325,7 @@
   yaml::StringValue Dest;
   raw_string_ostream OS(Dest.Value);
   OS << printReg(Reg, &TRI);
+  OS.flush();
   return Dest;
 }