--- a/lib/Option/Option.cpp	Tue Oct 13 17:49:56 2015 +0900
+++ b/lib/Option/Option.cpp	Tue Jan 26 22:53:40 2016 +0900
@@ -11,6 +11,7 @@
 #include "llvm/ADT/Twine.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
+#include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
@@ -35,10 +36,10 @@
   }
 }
 
-void Option::dump() const {
-  llvm::errs() << "<";
+void Option::print(raw_ostream &O) const {
+  O << "<";
   switch (getKind()) {
-#define P(N) case N: llvm::errs() << #N; break
+#define P(N) case N: O << #N; break
     P(GroupClass);
     P(InputClass);
     P(UnknownClass);
@@ -54,33 +55,35 @@
   }
 
   if (Info->Prefixes) {
-    llvm::errs() << " Prefixes:[";
-    for (const char * const *Pre = Info->Prefixes; *Pre != nullptr; ++Pre) {
-      llvm::errs() << '"' << *Pre << (*(Pre + 1) == nullptr ? "\"" : "\", ");
+    O << " Prefixes:[";
+    for (const char *const *Pre = Info->Prefixes; *Pre != nullptr; ++Pre) {
+      O << '"' << *Pre << (*(Pre + 1) == nullptr ? "\"" : "\", ");
     }
-    llvm::errs() << ']';
+    O << ']';
   }
 
-  llvm::errs() << " Name:\"" << getName() << '"';
+  O << " Name:\"" << getName() << '"';
 
   const Option Group = getGroup();
   if (Group.isValid()) {
-    llvm::errs() << " Group:";
-    Group.dump();
+    O << " Group:";
+    Group.print(O);
   }
 
   const Option Alias = getAlias();
   if (Alias.isValid()) {
-    llvm::errs() << " Alias:";
-    Alias.dump();
+    O << " Alias:";
+    Alias.print(O);
   }
 
   if (getKind() == MultiArgClass)
-    llvm::errs() << " NumArgs:" << getNumArgs();
+    O << " NumArgs:" << getNumArgs();
 
-  llvm::errs() << ">\n";
+  O << ">\n";
 }
 
+void Option::dump() const { print(dbgs()); }
+
 bool Option::matches(OptSpecifier Opt) const {
   // Aliases are never considered in matching, look through them.
   const Option Alias = getAlias();