diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index a76770063657..8bb834b45ed3 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -778,19 +778,16 @@ Currently, only the following parameter attributes are defined:
 .. Warning:: This feature is unstable and not fully implemented.
 
     The ``inalloca`` argument attribute allows the caller to take the
-    address of all stack-allocated arguments to a ``call`` or ``invoke``
-    before it executes.  It is similar to ``byval`` in that it is used
-    to pass arguments by value, but it guarantees that the argument will
-    not be copied.
+    address of outgoing stack arguments.  An ``inalloca`` argument must
+    be a pointer to stack memory produced by an ``alloca`` instruction.
+    The alloca, or argument allocation, must also be tagged with the
+    inalloca keyword.  Only the past argument may have the ``inalloca``
+    attribute, and that argument is guaranteed to be passed in memory.
 
-    To be :ref:`well formed <wellformed>`, an alloca may be used as an
-    ``inalloca`` argument at most once.  The attribute can only be
-    applied to the last parameter, and it guarantees that they are
-    passed in memory.  The ``inalloca`` attribute cannot be used in
-    conjunction with other attributes that affect argument storage, like
-    ``inreg``, ``nest``, ``sret``, or ``byval``.  The ``inalloca`` stack
-    space is considered to be clobbered by any call that uses it, so any
-    ``inalloca`` parameters cannot be marked ``readonly``.
+    An argument allocation may be used by a call at most once because
+    the call may deallocate it.  The ``inalloca`` attribute cannot be
+    used in conjunction with other attributes that affect argument
+    storage, like ``inreg``, ``nest``, ``sret``, or ``byval``.
 
     When the call site is reached, the argument allocation must have
     been the most recent stack allocation that is still live, or the
@@ -4693,7 +4690,7 @@ Syntax:
 
 ::
 
-      <result> = alloca <type>[, <ty> <NumElements>][, align <alignment>]     ; yields {type*}:result
+      <result> = alloca <type>[, inalloca][, <ty> <NumElements>][, align <alignment>]     ; yields {type*}:result
 
 Overview:
 """""""""
diff --git a/llvm/include/llvm/IR/Argument.h b/llvm/include/llvm/IR/Argument.h
index 9ba51bc21374..7c1ebf6dfffd 100644
--- a/llvm/include/llvm/IR/Argument.h
+++ b/llvm/include/llvm/IR/Argument.h
@@ -59,6 +59,11 @@ public:
   /// containing function.
   bool hasByValAttr() const;
 
+  /// \brief Return true if this argument has the byval attribute or inalloca
+  /// attribute on it in its containing function.  These attributes both
+  /// represent arguments being passed by value.
+  bool hasByValOrInAllocaAttr() const;
+
   /// \brief If this is a byval or inalloca argument, return its alignment.
   unsigned getParamAlignment() const;
 
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 0843d8fca3e2..eeea9945e8a4 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -101,7 +101,7 @@ public:
   /// by the instruction.
   ///
   unsigned getAlignment() const {
-    return (1u << getSubclassDataFromInstruction()) >> 1;
+    return (1u << (getSubclassDataFromInstruction() & 31)) >> 1;
   }
   void setAlignment(unsigned Align);
 
@@ -110,6 +110,20 @@ public:
   /// into the prolog/epilog code, so it is basically free.
   bool isStaticAlloca() const;
 
+  /// \brief Return true if this alloca is used as an inalloca argument to a
+  /// call.  Such allocas are never considered static even if they are in the
+  /// entry block.
+  bool isUsedWithInAlloca() const {
+    return getSubclassDataFromInstruction() & 32;
+  }
+
+  /// \brief Specify whether this alloca is used to represent a the arguments to
+  /// a call.
+  void setUsedWithInAlloca(bool V) {
+    setInstructionSubclassData((getSubclassDataFromInstruction() & ~32) |
+                               (V ? 32 : 0));
+  }
+
   // Methods for support type inquiry through isa, cast, and dyn_cast:
   static inline bool classof(const Instruction *I) {
     return (I->getOpcode() == Instruction::Alloca);
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index a1b5f9946c96..ab4b48bf6eca 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -4069,31 +4069,42 @@ bool LLParser::ParseCall(Instruction *&Inst, PerFunctionState &PFS,
 //===----------------------------------------------------------------------===//
 
 /// ParseAlloc
-///   ::= 'alloca' Type (',' TypeAndValue)? (',' OptionalInfo)?
+///   ::= 'alloca' Type (',' 'inalloca')? (',' TypeAndValue)? (',' OptionalInfo)?
 int LLParser::ParseAlloc(Instruction *&Inst, PerFunctionState &PFS) {
   Value *Size = 0;
   LocTy SizeLoc;
   unsigned Alignment = 0;
+  bool IsInAlloca = false;
   Type *Ty = 0;
   if (ParseType(Ty)) return true;
 
   bool AteExtraComma = false;
   if (EatIfPresent(lltok::comma)) {
-    if (Lex.getKind() == lltok::kw_align) {
-      if (ParseOptionalAlignment(Alignment)) return true;
-    } else if (Lex.getKind() == lltok::MetadataVar) {
-      AteExtraComma = true;
-    } else {
-      if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
-          ParseOptionalCommaAlign(Alignment, AteExtraComma))
-        return true;
+    bool HaveComma = true;
+    if (EatIfPresent(lltok::kw_inalloca)) {
+      IsInAlloca = true;
+      HaveComma = EatIfPresent(lltok::comma);
+    }
+
+    if (HaveComma) {
+      if (Lex.getKind() == lltok::kw_align) {
+        if (ParseOptionalAlignment(Alignment)) return true;
+      } else if (Lex.getKind() == lltok::MetadataVar) {
+        AteExtraComma = true;
+      } else {
+        if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
+            ParseOptionalCommaAlign(Alignment, AteExtraComma))
+          return true;
+      }
     }
   }
 
   if (Size && !Size->getType()->isIntegerTy())
     return Error(SizeLoc, "element count must have integer type");
 
-  Inst = new AllocaInst(Ty, Size, Alignment);
+  AllocaInst *AI = new AllocaInst(Ty, Size, Alignment);
+  AI->setUsedWithInAlloca(IsInAlloca);
+  Inst = AI;
   return AteExtraComma ? InstExtraComma : InstNormal;
 }
 
diff --git a/llvm/lib/AsmParser/LLParser.h b/llvm/lib/AsmParser/LLParser.h
index c62979e6f29e..d25374ff0531 100644
--- a/llvm/lib/AsmParser/LLParser.h
+++ b/llvm/lib/AsmParser/LLParser.h
@@ -211,6 +211,7 @@ namespace llvm {
                                AtomicOrdering &Ordering);
     bool ParseOptionalStackAlignment(unsigned &Alignment);
     bool ParseOptionalCommaAlign(unsigned &Alignment, bool &AteExtraComma);
+    bool ParseOptionalCommaInAlloca(bool &IsInAlloca);
     bool ParseIndexList(SmallVectorImpl<unsigned> &Indices,bool &AteExtraComma);
     bool ParseIndexList(SmallVectorImpl<unsigned> &Indices) {
       bool AteExtraComma;
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index bb6bef7bd026..c1fa3720e3f2 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -92,6 +92,13 @@ bool Argument::hasInAllocaAttr() const {
     hasAttribute(getArgNo()+1, Attribute::InAlloca);
 }
 
+bool Argument::hasByValOrInAllocaAttr() const {
+  if (!getType()->isPointerTy()) return false;
+  AttributeSet Attrs = getParent()->getAttributes();
+  return Attrs.hasAttribute(getArgNo() + 1, Attribute::ByVal) ||
+         Attrs.hasAttribute(getArgNo() + 1, Attribute::InAlloca);
+}
+
 unsigned Argument::getParamAlignment() const {
   assert(getType()->isPointerTy() && "Only pointers have alignments");
   return getParent()->getParamAlignment(getArgNo()+1);
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 761f60063fab..5a50b7365005 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -893,7 +893,8 @@ void AllocaInst::setAlignment(unsigned Align) {
   assert((Align & (Align-1)) == 0 && "Alignment is not a power of 2!");
   assert(Align <= MaximumAlignment &&
          "Alignment is greater than MaximumAlignment!");
-  setInstructionSubclassData(Log2_32(Align) + 1);
+  setInstructionSubclassData((getSubclassDataFromInstruction() & ~31) |
+                             (Log2_32(Align) + 1));
   assert(getAlignment() == Align && "Alignment representation error!");
 }
 
@@ -916,7 +917,7 @@ bool AllocaInst::isStaticAlloca() const {
   
   // Must be in the entry block.
   const BasicBlock *Parent = getParent();
-  return Parent == &Parent->getParent()->front();
+  return Parent == &Parent->getParent()->front() && !isUsedWithInAlloca();
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/llvm/test/Assembler/inalloca.ll b/llvm/test/Assembler/inalloca.ll
new file mode 100644
index 000000000000..94fac26265c4
--- /dev/null
+++ b/llvm/test/Assembler/inalloca.ll
@@ -0,0 +1,16 @@
+; RUN: llvm-as %s -o /dev/null
+
+define void @a() {
+entry:
+  %0 = alloca i32, inalloca
+  %1 = alloca [2 x i32], inalloca
+  %2 = alloca i32, inalloca, i32 2
+  %3 = alloca i32, inalloca, i32 2, align 16
+  %4 = alloca i32, inalloca, i32 2, align 16, !foo !0
+  %5 = alloca i32, i32 2, align 16, !foo !0
+  %6 = alloca i32, i32 2, align 16
+  ret void
+}
+
+!0 = metadata !{i32 662302, null}
+!foo = !{ !0 }
diff --git a/llvm/test/Verifier/inalloca-vararg.ll b/llvm/test/Verifier/inalloca-vararg.ll
index 6729c4283046..8521ebce2d9c 100755
--- a/llvm/test/Verifier/inalloca-vararg.ll
+++ b/llvm/test/Verifier/inalloca-vararg.ll
@@ -2,7 +2,7 @@
 
 declare void @h(i32, ...)
 define void @i() {
-  %args = alloca i32
+  %args = alloca i32, inalloca
   call void (i32, ...)* @h(i32 1, i32* inalloca %args, i32 3)
 ; CHECK: inalloca isn't on the last argument!
   ret void
diff --git a/llvm/test/Verifier/inalloca2.ll b/llvm/test/Verifier/inalloca2.ll
index ed65667dc308..e4e81be38615 100644
--- a/llvm/test/Verifier/inalloca2.ll
+++ b/llvm/test/Verifier/inalloca2.ll
@@ -6,7 +6,7 @@ declare void @doit(i64* inalloca %a)
 
 define void @a() {
 entry:
-  %a = alloca [2 x i32]
+  %a = alloca [2 x i32], inalloca
   %b = bitcast [2 x i32]* %a to i64*
   call void @doit(i64* inalloca %b)
   ret void
@@ -14,8 +14,26 @@ entry:
 
 define void @b() {
 entry:
-  %a = alloca i64
+  %a = alloca i64, inalloca
   call void @doit(i64* inalloca %a)
   call void @doit(i64* inalloca %a)
   ret void
 }
+
+define void @c(i1 %cond) {
+entry:
+  br i1 %cond, label %if, label %else
+
+if:
+  %a = alloca i64, inalloca
+  br label %call
+
+else:
+  %b = alloca i64, inalloca
+  br label %call
+
+call:
+  %args = phi i64* [ %a, %if ], [ %b, %else ]
+  call void @doit(i64* inalloca %args)
+  ret void
+}