Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -874,6 +874,17 @@
     This function attribute indicates that the function never returns
     with an unwind or exceptional control flow. If the function does
     unwind, its runtime behavior is undefined.
+``optnone``
+    This function attribute indicates that the function is not optimized
+    by any optimization or code generator passes with the 
+    exception of interprocedural optimization passes.
+    This attribute cannot be used together with the ``alwaysinline``
+    attribute; this attribute is also incompatible
+    with the ``minsize`` attribute and the ``optsize`` attribute.
+    
+    The inliner should never inline this function in any situation.
+    Only functions with the ``alwaysinline`` attribute are valid
+    candidates for inlining inside the body of this function.
 ``optsize``
     This attribute suggests that optimization passes and code generator
     passes make choices that keep the code size of this function low,
Index: include/llvm-c/Core.h
===================================================================
--- include/llvm-c/Core.h
+++ include/llvm-c/Core.h
@@ -165,8 +165,9 @@
        a temporary measure until the API/ABI impact to the C API is understood
        and the path forward agreed upon.
     LLVMAddressSafety = 1ULL << 32,
-    LLVMStackProtectStrongAttribute = 1ULL<<33
-    LLVMCold = 1ULL << 34
+    LLVMStackProtectStrongAttribute = 1ULL<<33,
+    LLVMCold = 1ULL << 34,
+    LLVMOptimizeNone = 1ULL << 35
     */
 } LLVMAttribute;
 
Index: include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- include/llvm/Bitcode/LLVMBitCodes.h
+++ include/llvm/Bitcode/LLVMBitCodes.h
@@ -368,7 +368,8 @@
     ATTR_KIND_UW_TABLE = 33,
     ATTR_KIND_Z_EXT = 34,
     ATTR_KIND_BUILTIN = 35,
-    ATTR_KIND_COLD = 36
+    ATTR_KIND_COLD = 36,
+    ATTR_KIND_OPTIMIZE_NONE = 37
   };
 
 } // End bitc namespace
Index: include/llvm/IR/Attributes.h
===================================================================
--- include/llvm/IR/Attributes.h
+++ include/llvm/IR/Attributes.h
@@ -88,6 +88,7 @@
     NoReturn,              ///< Mark the function as not returning
     NoUnwind,              ///< Function doesn't unwind stack
     OptimizeForSize,       ///< opt_size
+    OptimizeNone,          ///< Function must not be optimized.
     ReadNone,              ///< Function does not access memory
     ReadOnly,              ///< Function only reads from memory
     Returned,              ///< Return value is always equal to this argument
Index: lib/AsmParser/LLLexer.cpp
===================================================================
--- lib/AsmParser/LLLexer.cpp
+++ lib/AsmParser/LLLexer.cpp
@@ -583,6 +583,7 @@
   KEYWORD(noredzone);
   KEYWORD(noreturn);
   KEYWORD(nounwind);
+  KEYWORD(optnone);
   KEYWORD(optsize);
   KEYWORD(readnone);
   KEYWORD(readonly);
Index: lib/AsmParser/LLParser.cpp
===================================================================
--- lib/AsmParser/LLParser.cpp
+++ lib/AsmParser/LLParser.cpp
@@ -922,6 +922,7 @@
     case lltok::kw_noredzone:         B.addAttribute(Attribute::NoRedZone); break;
     case lltok::kw_noreturn:          B.addAttribute(Attribute::NoReturn); break;
     case lltok::kw_nounwind:          B.addAttribute(Attribute::NoUnwind); break;
+    case lltok::kw_optnone:           B.addAttribute(Attribute::OptimizeNone); break;
     case lltok::kw_optsize:           B.addAttribute(Attribute::OptimizeForSize); break;
     case lltok::kw_readnone:          B.addAttribute(Attribute::ReadNone); break;
     case lltok::kw_readonly:          B.addAttribute(Attribute::ReadOnly); break;
@@ -1180,6 +1181,7 @@
     case lltok::kw_noredzone:
     case lltok::kw_noreturn:
     case lltok::kw_nounwind:
+    case lltok::kw_optnone:
     case lltok::kw_optsize:
     case lltok::kw_returns_twice:
     case lltok::kw_sanitize_address:
@@ -1238,6 +1240,7 @@
     case lltok::kw_noredzone:
     case lltok::kw_noreturn:
     case lltok::kw_nounwind:
+    case lltok::kw_optnone:
     case lltok::kw_optsize:
     case lltok::kw_returns_twice:
     case lltok::kw_sanitize_address:
Index: lib/AsmParser/LLToken.h
===================================================================
--- lib/AsmParser/LLToken.h
+++ lib/AsmParser/LLToken.h
@@ -114,6 +114,7 @@
     kw_noredzone,
     kw_noreturn,
     kw_nounwind,
+    kw_optnone,
     kw_optsize,
     kw_readnone,
     kw_readonly,
Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -573,6 +573,9 @@
   case bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE:
     *Kind = Attribute::OptimizeForSize;
     return false;
+  case bitc::ATTR_KIND_OPTIMIZE_NONE:
+    *Kind = Attribute::OptimizeNone;
+    return false;
   case bitc::ATTR_KIND_READ_NONE:
     *Kind = Attribute::ReadNone;
     return false;
Index: lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- lib/Bitcode/Writer/BitcodeWriter.cpp
+++ lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -205,6 +205,8 @@
     return bitc::ATTR_KIND_NO_UNWIND;
   case Attribute::OptimizeForSize:
     return bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE;
+  case Attribute::OptimizeNone:
+    return bitc::ATTR_KIND_OPTIMIZE_NONE;
   case Attribute::ReadNone:
     return bitc::ATTR_KIND_READ_NONE;
   case Attribute::ReadOnly:
Index: lib/IR/Attributes.cpp
===================================================================
--- lib/IR/Attributes.cpp
+++ lib/IR/Attributes.cpp
@@ -196,6 +196,8 @@
     return "noreturn";
   if (hasAttribute(Attribute::NoUnwind))
     return "nounwind";
+  if (hasAttribute(Attribute::OptimizeNone))
+    return "optnone";
   if (hasAttribute(Attribute::OptimizeForSize))
     return "optsize";
   if (hasAttribute(Attribute::ReadNone))
@@ -381,6 +383,7 @@
   case Attribute::Returned:        return 1ULL << 39;
   case Attribute::Cold:            return 1ULL << 40;
   case Attribute::Builtin:         return 1ULL << 41;
+  case Attribute::OptimizeNone:    return 1ULL << 42;
   }
   llvm_unreachable("Unsupported attribute type");
 }
Index: lib/IR/Verifier.cpp
===================================================================
--- lib/IR/Verifier.cpp
+++ lib/IR/Verifier.cpp
@@ -751,7 +751,8 @@
         I->getKindAsEnum() == Attribute::NoDuplicate ||
         I->getKindAsEnum() == Attribute::Builtin ||
         I->getKindAsEnum() == Attribute::NoBuiltin ||
-        I->getKindAsEnum() == Attribute::Cold) {
+        I->getKindAsEnum() == Attribute::Cold ||
+        I->getKindAsEnum() == Attribute::OptimizeNone) {
       if (!isFunction) {
         CheckFailed("Attribute '" + I->getAsString() +
                     "' only applies to functions!", V);
@@ -897,6 +898,21 @@
             Attrs.hasAttribute(AttributeSet::FunctionIndex,
                                Attribute::AlwaysInline)),
           "Attributes 'noinline and alwaysinline' are incompatible!", V);
+
+  if (Attrs.hasAttribute(AttributeSet::FunctionIndex, 
+                         Attribute::OptimizeNone)) {
+    Assert1(!Attrs.hasAttribute(AttributeSet::FunctionIndex,
+                                Attribute::AlwaysInline),
+            "Attributes 'alwaysinline and optnone' are incompatible!", V);
+
+    Assert1(!Attrs.hasAttribute(AttributeSet::FunctionIndex,
+                                Attribute::OptimizeForSize),
+            "Attributes 'optsize and optnone' are incompatible!", V);
+
+    Assert1(!Attrs.hasAttribute(AttributeSet::FunctionIndex,
+                                Attribute::MinSize),
+            "Attributes 'minsize and optnone' are incompatible!", V);
+  }
 }
 
 void Verifier::VerifyBitcastType(const Value *V, Type *DestTy, Type *SrcTy) {
Index: lib/Target/CppBackend/CPPBackend.cpp
===================================================================
--- lib/Target/CppBackend/CPPBackend.cpp
+++ lib/Target/CppBackend/CPPBackend.cpp
@@ -497,6 +497,7 @@
       HANDLE_ATTR(ReadOnly);
       HANDLE_ATTR(NoInline);
       HANDLE_ATTR(AlwaysInline);
+      HANDLE_ATTR(OptimizeNone);
       HANDLE_ATTR(OptimizeForSize);
       HANDLE_ATTR(StackProtect);
       HANDLE_ATTR(StackProtectReq);
Index: test/Bitcode/attributes.ll
===================================================================
--- test/Bitcode/attributes.ll
+++ test/Bitcode/attributes.ll
@@ -203,10 +203,16 @@
 ; CHECK: define void @f34()
 {
         call void @nobuiltin() nobuiltin
-; CHECK: call void @nobuiltin() #23
+; CHECK: call void @nobuiltin() #24
         ret void;
 }
 
+define void @f35() optnone
+; CHECK: define void @f35() #23
+{
+        ret void;
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -230,4 +236,6 @@
 ; CHECK: attributes #20 = { "cpu"="cortex-a8" }
 ; CHECK: attributes #21 = { sspstrong }
 ; CHECK: attributes #22 = { minsize }
-; CHECK: attributes #23 = { nobuiltin }
+; CHECK: attributes #23 = { optnone }
+; CHECK: attributes #24 = { nobuiltin }
+
Index: test/Feature/optnone.ll
===================================================================
--- test/Feature/optnone.ll
+++ test/Feature/optnone.ll
@@ -0,0 +1,12 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+
+; Check for the presence of attribute noopt in the disassembly.
+
+; CHECK: @foo() #0
+define void @foo() #0 {
+  ret void
+}
+
+; CHECK: attributes #0 = { optnone }
+attributes #0 = { optnone }
+
Index: utils/kate/llvm.xml
===================================================================
--- utils/kate/llvm.xml
+++ utils/kate/llvm.xml
@@ -85,6 +85,7 @@
       <item> noredzone </item>
       <item> noreturn </item>
       <item> nounwind </item>
+      <item> optnone </item>
       <item> optsize </item>
       <item> readnone </item>
       <item> readonly </item>
Index: utils/vim/llvm.vim
===================================================================
--- utils/vim/llvm.vim
+++ utils/vim/llvm.vim
@@ -48,7 +48,7 @@
 syn keyword llvmKeyword localdynamic localexec minsize module monotonic
 syn keyword llvmKeyword msp430_intrcc naked nest noalias nocapture
 syn keyword llvmKeyword noimplicitfloat noinline nonlazybind noredzone noreturn
-syn keyword llvmKeyword nounwind optsize personality private protected
+syn keyword llvmKeyword nounwind optnone optsize personality private protected
 syn keyword llvmKeyword ptx_device ptx_kernel readnone readonly release
 syn keyword llvmKeyword returns_twice sanitize_thread sanitize_memory
 syn keyword llvmKeyword section seq_cst sideeffect signext singlethread