diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 1761d7faff576315c0fbb81e299ac4d9f08030f6..5518ef8fce988d626522324a3bf80070c87990b3 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -2107,6 +2107,13 @@ static bool hasChangeableCC(Function *F) {
   if (CC != CallingConv::C && CC != CallingConv::X86_ThisCall)
     return false;
 
+  // Don't break the invariant that the inalloca parameter is the only parameter
+  // passed in memory.
+  // FIXME: GlobalOpt should remove inalloca when possible and hoist the dynamic
+  // alloca it uses to the entry block if possible.
+  if (F->getAttributes().hasAttrSomewhere(Attribute::InAlloca))
+    return false;
+
   // FIXME: Change CC for the whole chain of musttail calls when possible.
   //
   // Can't change CC of the function that either has musttail calls, or is a
diff --git a/llvm/test/Transforms/GlobalOpt/fastcc.ll b/llvm/test/Transforms/GlobalOpt/fastcc.ll
index 26398d2bb900100969a79a74bffaca62931b4122..64c4a268ff3cba918897f43d462c90633e2b2f09 100644
--- a/llvm/test/Transforms/GlobalOpt/fastcc.ll
+++ b/llvm/test/Transforms/GlobalOpt/fastcc.ll
@@ -26,12 +26,20 @@ define internal i32 @j(i32* %m) {
   ret i32 %v
 }
 
+define internal i32 @inalloca(i32* inalloca %p) {
+; CHECK-LABEL: define internal i32 @inalloca(i32* inalloca %p)
+  %rv = load i32, i32* %p
+  ret i32 %rv
+}
+
 define void @call_things() {
   %m = alloca i32
   call i32 @f(i32* %m)
   call x86_thiscallcc i32 @g(i32* %m)
   call coldcc i32 @h(i32* %m)
   call i32 @j(i32* %m)
+  %args = alloca inalloca i32
+  call i32 @inalloca(i32* inalloca %args)
   ret void
 }
 
@@ -44,3 +52,4 @@ define void @call_things() {
 ; CHECK: call fastcc i32 @g
 ; CHECK: call coldcc i32 @h
 ; CHECK: call i32 @j
+; CHECK: call i32 @inalloca(i32* inalloca %args)