Index: include/llvm/Support/Error.h
===================================================================
--- include/llvm/Support/Error.h
+++ include/llvm/Support/Error.h
@@ -302,6 +302,14 @@
     return Tmp;
   }
 
+  friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) {
+    if (auto P = E.getPtr())
+      P->log(OS);
+    else
+      OS << "success";
+    return OS;
+  }
+
   ErrorInfoBase *Payload = nullptr;
 };
 
Index: include/llvm/Support/FormatProviders.h
===================================================================
--- include/llvm/Support/FormatProviders.h
+++ include/llvm/Support/FormatProviders.h
@@ -418,6 +418,12 @@
     }
   }
 };
-}
+
+class Error;
+template <> struct llvm::format_provider<llvm::Error> {
+  static void format(const llvm::Error &, llvm::raw_ostream &, StringRef Style);
+};
+
+} // namespace llvm
 
 #endif
Index: include/llvm/Support/FormatVariadic.h
===================================================================
--- include/llvm/Support/FormatVariadic.h
+++ include/llvm/Support/FormatVariadic.h
@@ -261,7 +261,14 @@
 // Allow a formatv_object to be formatted (no options supported).
 template <typename T> struct format_provider<formatv_object<T>> {
   static void format(const formatv_object<T> &V, raw_ostream &OS, StringRef) {
-    OS << V;
+    V.format(OS);
+  }
+};
+
+// Allow a formatv_object to be formatted (no options supported).
+template <> struct format_provider<formatv_object_base> {
+  static void format(const formatv_object_base &V, raw_ostream &OS, StringRef) {
+    V.format(OS);
   }
 };
 
Index: lib/Support/CMakeLists.txt
===================================================================
--- lib/Support/CMakeLists.txt
+++ lib/Support/CMakeLists.txt
@@ -75,6 +75,7 @@
   FileOutputBuffer.cpp
   FoldingSet.cpp
   FormattedStream.cpp
+  FormatProviders.cpp
   FormatVariadic.cpp
   GlobPattern.cpp
   GraphWriter.cpp
Index: lib/Support/FormatProviders.cpp
===================================================================
--- /dev/null
+++ lib/Support/FormatProviders.cpp
@@ -0,0 +1,19 @@
+//===- FormatProviders.cpp - Formatters for common LLVM types -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/FormatProviders.h"
+#include "llvm/Support/Error.h"
+
+namespace llvm {
+void format_provider<llvm::Error>::format(const llvm::Error &Err,
+                                          llvm::raw_ostream &OS,
+                                          StringRef Style) {
+  OS << Err;
+}
+} // namespace llvm
Index: unittests/Support/FormatVariadicTest.cpp
===================================================================
--- unittests/Support/FormatVariadicTest.cpp
+++ unittests/Support/FormatVariadicTest.cpp
@@ -8,6 +8,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/FormatVariadic.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/FormatAdapters.h"
 #include "gtest/gtest.h"
 
@@ -646,6 +647,16 @@
   EXPECT_EQ("[   ! ]", formatv("[{0,+5}]", formatv("{0,-2}", "!")).str());
 }
 
+TEST(FormatVariadicTest, FormatError) {
+  Error Bad = make_error<StringError>("oh no!", inconvertibleErrorCode());
+  Error OK = Error::success();
+  EXPECT_EQ("oh no!", formatv("{0}", Bad).str());
+  EXPECT_EQ("success", formatv("{0}", OK).str());
+  // formatv takes a const Error&, and does not consume it.
+  consumeError(std::move(Bad));
+  consumeError(std::move(OK));
+}
+
 namespace {
 struct Recorder {
   int Copied = 0, Moved = 0;