Index: lib/Target/X86/X86FastISel.cpp
===================================================================
--- lib/Target/X86/X86FastISel.cpp
+++ lib/Target/X86/X86FastISel.cpp
@@ -2983,9 +2983,9 @@
   return true;
 }
 
-static unsigned computeBytesPoppedByCallee(const X86Subtarget *Subtarget,
-                                           CallingConv::ID CC,
-                                           ImmutableCallSite *CS) {
+static unsigned computeBytesPoppedByCalleeForSRet(const X86Subtarget *Subtarget,
+                                                  CallingConv::ID CC,
+                                                  ImmutableCallSite *CS) {
   if (Subtarget->is64Bit())
     return 0;
   if (Subtarget->getTargetTriple().isOSMSVCRT())
@@ -3025,6 +3025,7 @@
   case CallingConv::WebKit_JS:
   case CallingConv::Swift:
   case CallingConv::X86_FastCall:
+  case CallingConv::X86_ThisCall:
   case CallingConv::X86_64_Win64:
   case CallingConv::X86_64_SysV:
     break;
@@ -3052,11 +3053,6 @@
     if (Flag.isSwiftError())
       return false;
 
-  // Fast-isel doesn't know about callee-pop yet.
-  if (X86::isCalleePop(CC, Subtarget->is64Bit(), IsVarArg,
-                       TM.Options.GuaranteedTailCallOpt))
-    return false;
-
   SmallVector<MVT, 16> OutVTs;
   SmallVector<unsigned, 16> ArgRegs;
 
@@ -3336,7 +3332,10 @@
 
   // Issue CALLSEQ_END
   unsigned NumBytesForCalleeToPop =
-    computeBytesPoppedByCallee(Subtarget, CC, CLI.CS);
+      X86::isCalleePop(CC, Subtarget->is64Bit(), IsVarArg,
+                       TM.Options.GuaranteedTailCallOpt)
+          ? NumBytes // Callee pops everything.
+          : computeBytesPoppedByCalleeForSRet(Subtarget, CC, CLI.CS);
   unsigned AdjStackUp = TII.getCallFrameDestroyOpcode();
   BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(AdjStackUp))
     .addImm(NumBytes).addImm(NumBytesForCalleeToPop);
Index: test/CodeGen/X86/fast-isel-call.ll
===================================================================
--- test/CodeGen/X86/fast-isel-call.ll
+++ test/CodeGen/X86/fast-isel-call.ll
@@ -1,4 +1,5 @@
-; RUN: llc < %s -O0 -fast-isel-abort=1 -march=x86 -mtriple=i686-apple-darwin8 | FileCheck %s
+; RUN: llc < %s -O0 -fast-isel-abort=1 -march=x86 -mtriple=i686-apple-darwin8 2>/dev/null | FileCheck %s
+; RUN: llc < %s -O0 -fast-isel-abort=1 -march=x86 -mtriple=i686-apple-darwin8 2>&1 >/dev/null | FileCheck -check-prefix=STDERR -allow-empty %s
 
 %struct.s = type {i32, i32, i32}
 
@@ -53,3 +54,19 @@
 ; CHECK:   movl	$100, 8(%esp)
 ; CHECK:   calll {{.*}}memcpy
 }
+
+; STDERR-NOT: FastISel missed call:   call x86_thiscallcc void @thiscallfun
+%struct.S = type { i8 }
+define void @test5() #0 {
+entry:
+  %s = alloca %struct.S, align 1
+; CHECK-LABEL: test5:
+; CHECK: subl $12, %esp
+; CHECK: leal 8(%esp), %ecx
+; CHECK: movl $43, (%esp)
+; CHECK: calll {{.*}}thiscallfun
+; CHECK: addl $8, %esp
+  call x86_thiscallcc void @thiscallfun(%struct.S* %s, i32 43)
+  ret void
+}
+declare x86_thiscallcc void @thiscallfun(%struct.S*, i32) #1