diff --git a/include/llvm/Function.h b/include/llvm/Function.h
index 2b19fa5..9a0825a 100644
--- a/include/llvm/Function.h
+++ b/include/llvm/Function.h
@@ -152,7 +152,7 @@
   /// The particular intrinsic functions which correspond to this value are
   /// defined in llvm/Intrinsics.h.
   ///
-  unsigned getIntrinsicID() const ATTRIBUTE_READONLY;
+  unsigned getIntrinsicID() const LLVM_ATTRIBUTE_READONLY;
   bool isIntrinsic() const { return getIntrinsicID() != 0; }
 
   /// getCallingConv()/setCallingConv(CC) - These method get and set the
diff --git a/include/llvm/Support/Compiler.h b/include/llvm/Support/Compiler.h
index 014e801..83facc3 100644
--- a/include/llvm/Support/Compiler.h
+++ b/include/llvm/Support/Compiler.h
@@ -26,9 +26,9 @@
 #endif
 
 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
-#define ATTRIBUTE_USED __attribute__((__used__))
+#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
 #else
-#define ATTRIBUTE_USED
+#define LLVM_ATTRIBUTE_USED
 #endif
 
 // Some compilers warn about unused functions. When a function is sometimes
@@ -40,21 +40,21 @@
 //   (void)unused_var_name;
 // Prefer cast-to-void wherever it is sufficient.
 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
-#define ATTRIBUTE_UNUSED __attribute__((__unused__))
+#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
 #else
-#define ATTRIBUTE_UNUSED
+#define LLVM_ATTRIBUTE_UNUSED
 #endif
 
 #ifdef __GNUC__ // aka 'ATTRIBUTE_CONST' but following LLVM Conventions.
-#define ATTRIBUTE_READNONE __attribute__((__const__))
+#define LLVM_ATTRIBUTE_READNONE __attribute__((__const__))
 #else
-#define ATTRIBUTE_READNONE
+#define LLVM_ATTRIBUTE_READNONE
 #endif
 
 #ifdef __GNUC__  // aka 'ATTRIBUTE_PURE' but following LLVM Conventions.
-#define ATTRIBUTE_READONLY __attribute__((__pure__))
+#define LLVM_ATTRIBUTE_READONLY __attribute__((__pure__))
 #else
-#define ATTRIBUTE_READONLY
+#define LLVM_ATTRIBUTE_READONLY
 #endif
 
 #if (__GNUC__ >= 4)
@@ -107,4 +107,12 @@
 #define NORETURN
 #endif
 
+// We provide definitions without the LLVM_ prefix briefly while transitioning
+// to always-prefixed names. These will go away as soon as the migration is
+// complete.
+#define ATTRIBUTE_USED LLVM_ATTRIBUTE_USED
+#define ATTRIBUTE_UNUSED LLVM_ATTRIBUTE_UNUSED
+#define ATTRIBUTE_READNONE LLVM_ATTRIBUTE_READNONE
+#define ATTRIBUTE_READONLY LLVM_ATTRIBUTE_READONLY
+
 #endif
diff --git a/lib/Target/ARM/ARMExpandPseudoInsts.cpp b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
index 389fd19..4a7c771 100644
--- a/lib/Target/ARM/ARMExpandPseudoInsts.cpp
+++ b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
@@ -102,8 +102,8 @@
     friend bool operator<(const NEONLdStTableEntry &TE, unsigned PseudoOpc) {
       return TE.PseudoOpc < PseudoOpc;
     }
-    friend bool ATTRIBUTE_UNUSED operator<(unsigned PseudoOpc,
-                                           const NEONLdStTableEntry &TE) {
+    friend bool LLVM_ATTRIBUTE_UNUSED operator<(unsigned PseudoOpc,
+                                                const NEONLdStTableEntry &TE) {
       return PseudoOpc < TE.PseudoOpc;
     }
   };
diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp
index 05f0428..5da6d3a 100644
--- a/lib/Target/X86/X86FloatingPoint.cpp
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -575,7 +575,8 @@
     friend bool operator<(const TableEntry &TE, unsigned V) {
       return TE.from < V;
     }
-    friend bool ATTRIBUTE_USED operator<(unsigned V, const TableEntry &TE) {
+    friend bool LLVM_ATTRIBUTE_USED operator<(unsigned V,
+                                              const TableEntry &TE) {
       return V < TE.from;
     }
   };
diff --git a/lib/Target/X86/X86JITInfo.cpp b/lib/Target/X86/X86JITInfo.cpp
index 6f0a8d9..e83f359 100644
--- a/lib/Target/X86/X86JITInfo.cpp
+++ b/lib/Target/X86/X86JITInfo.cpp
@@ -337,7 +337,7 @@
  // no support for inline assembly
 static
 #endif
-void ATTRIBUTE_USED
+void LLVM_ATTRIBUTE_USED
 X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
   intptr_t *RetAddrLoc = &StackPtr[1];
   assert(*RetAddrLoc == RetAddr &&
diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp
index 6db53f4..914a439 100644
--- a/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/lib/Transforms/Utils/LowerSwitch.cpp
@@ -109,7 +109,8 @@
 // operator<< - Used for debugging purposes.
 //
 static raw_ostream& operator<<(raw_ostream &O,
-                               const LowerSwitch::CaseVector &C) ATTRIBUTE_USED;
+                               const LowerSwitch::CaseVector &C)
+    LLVM_ATTRIBUTE_USED;
 static raw_ostream& operator<<(raw_ostream &O,
                                const LowerSwitch::CaseVector &C) {
   O << "[";
diff --git a/unittests/ADT/SmallVectorTest.cpp b/unittests/ADT/SmallVectorTest.cpp
index 78dc393..f4da54d 100644
--- a/unittests/ADT/SmallVectorTest.cpp
+++ b/unittests/ADT/SmallVectorTest.cpp
@@ -77,7 +77,7 @@
     return c0.getValue() == c1.getValue();
   }
 
-  friend bool ATTRIBUTE_UNUSED
+  friend bool LLVM_ATTRIBUTE_UNUSED
   operator!=(const Constructable & c0, const Constructable & c1) {
     return c0.getValue() != c1.getValue();
   }