diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1392,6 +1392,13 @@
     alignments are permitted for the allocalign parameter, so long as the returned pointer
     is null. This attribute may only be applied to integer parameters.
 
+``allocptr``
+    The function parameter marked with this attribute is the pointer
+    that will be manipulated by the allocator. For a realloc-like
+    function the pointer will be invalidated upon success (but the
+    same address may be returned), for a free-like function the
+    pointer will always be invalidated.
+
 .. _gc:
 
 Garbage Collector Strategy Names
diff --git a/llvm/include/llvm/AsmParser/LLToken.h b/llvm/include/llvm/AsmParser/LLToken.h
--- a/llvm/include/llvm/AsmParser/LLToken.h
+++ b/llvm/include/llvm/AsmParser/LLToken.h
@@ -199,6 +199,7 @@
   kw_inreg,
   kw_jumptable,
   kw_minsize,
+  kw_allocptr,
   kw_naked,
   kw_nest,
   kw_noalias,
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -679,6 +679,7 @@
   ATTR_KIND_DISABLE_SANITIZER_INSTRUMENTATION = 78,
   ATTR_KIND_NO_SANITIZE_BOUNDS = 79,
   ATTR_KIND_ALLOC_ALIGN = 80,
+  ATTR_KIND_ALLOCATED_POINTER = 81,
 };
 
 enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -47,10 +47,13 @@
 /// 0 means unaligned (different from align(1)).
 def Alignment : IntAttr<"align", [ParamAttr, RetAttr]>;
 
-/// Parameter of a function that tells us the alignment of an allocation, as in 
+/// Parameter of a function that tells us the alignment of an allocation, as in
 /// aligned_alloc and aligned ::operator::new.
 def AllocAlign: EnumAttr<"allocalign", [ParamAttr]>;
 
+/// Parameter is the pointer to be maniuplated by the allocator function.
+def AllocatedPointer : EnumAttr<"allocptr", [ParamAttr]>;
+
 /// The result of the function is guaranteed to point to a number of bytes that
 /// we can determine if we know the value of the function's arguments.
 def AllocSize : IntAttr<"allocsize", [FnAttr]>;
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -652,6 +652,7 @@
   KEYWORD(inreg);
   KEYWORD(jumptable);
   KEYWORD(minsize);
+  KEYWORD(allocptr);
   KEYWORD(naked);
   KEYWORD(nest);
   KEYWORD(noalias);
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1526,6 +1526,8 @@
     return Attribute::AllocAlign;
   case bitc::ATTR_KIND_ALLOC_SIZE:
     return Attribute::AllocSize;
+  case bitc::ATTR_KIND_ALLOCATED_POINTER:
+    return Attribute::AllocatedPointer;
   case bitc::ATTR_KIND_NO_RED_ZONE:
     return Attribute::NoRedZone;
   case bitc::ATTR_KIND_NO_RETURN:
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -646,6 +646,8 @@
     return bitc::ATTR_KIND_JUMP_TABLE;
   case Attribute::MinSize:
     return bitc::ATTR_KIND_MIN_SIZE;
+  case Attribute::AllocatedPointer:
+    return bitc::ATTR_KIND_ALLOCATED_POINTER;
   case Attribute::Naked:
     return bitc::ATTR_KIND_NAKED;
   case Attribute::Nest:
diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -1803,7 +1803,9 @@
           .addAttribute(Attribute::ByVal)
           .addAttribute(Attribute::StructRet)
           .addAttribute(Attribute::ByRef)
-          .addAttribute(Attribute::ElementType);
+          .addAttribute(Attribute::ElementType)
+          // TODO(durin42): this might be safe to drop?
+          .addAttribute(Attribute::AllocatedPointer);
   }
 
     // Attributes that only apply to pointers or vectors of pointers.
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -963,6 +963,7 @@
         break;
       // These attributes cannot be applied to functions.
       case Attribute::Alignment:
+      case Attribute::AllocatedPointer:
       case Attribute::AllocAlign:
       case Attribute::ByVal:
       case Attribute::Dereferenceable:
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -562,6 +562,8 @@
 ; CHECK: declare void @f.param.swifterror(i8** swifterror)
 declare void @f.param.allocalign(i32 allocalign)
 ; CHECK: declare void @f.param.allocalign(i32 allocalign)
+declare void @f.param.allocptr(i32* allocptr)
+; CHECK: declare void @f.param.allocptr(i32* allocptr)
 
 ; Functions -- unnamed_addr and local_unnamed_addr
 declare void @f.unnamed_addr() unnamed_addr