Index: test/CodeGen/inline-asm-attr.c
===================================================================
--- test/CodeGen/inline-asm-attr.c	(revision 0)
+++ test/CodeGen/inline-asm-attr.c	(revision 0)
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -O3 -emit-llvm %s -o - | FileCheck %s
+
+__attribute__((const))
+static inline void **varptr(void) {
+    void *ptr;
+    asm("mov $0x12345678, %0" : "=r" (ptr));
+    return ptr;
+}
+static inline void *getvar(void) { return *varptr(); }
+static inline void setvar(void *value) { *varptr() = value; }
+
+void fn(void) {
+// CHECK: @fn
+// CHECK: entry
+// CHECK: tail call i8* asm 
+// CHECK: if.then
+// CHECK-NOT: tail call i8* asm 
+// CHECK-NOT: far from pukin 
+  if (getvar())
+    setvar(0);
+}
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp	(revision 155999)
+++ lib/CodeGen/CGStmt.cpp	(working copy)
@@ -1633,6 +1633,13 @@
                          S.isVolatile() || S.getNumOutputs() == 0);
   llvm::CallInst *Result = Builder.CreateCall(IA, Args);
   Result->addAttribute(~0, llvm::Attribute::NoUnwind);
+  
+  // Allow the inline assembly to inherit the ReadNone/ReadOnly attribute.
+  llvm::Function *Fn = Result->getParent()->getParent();
+  if (Fn->hasFnAttr(llvm::Attribute::ReadNone))
+    Result->addAttribute(~0, llvm::Attribute::ReadNone);
+  if (Fn->hasFnAttr(llvm::Attribute::ReadOnly))
+    Result->addAttribute(~0, llvm::Attribute::ReadOnly);  
 
   // Slap the source location of the inline asm into a !srcloc metadata on the
   // call.