diff --git a/llvm/lib/Target/AVR/AVRCallingConv.td b/llvm/lib/Target/AVR/AVRCallingConv.td
--- a/llvm/lib/Target/AVR/AVRCallingConv.td
+++ b/llvm/lib/Target/AVR/AVRCallingConv.td
@@ -38,4 +38,4 @@
 //===----------------------------------------------------------------------===//
 
 def CSR_Normal : CalleeSavedRegs<(add R29, R28, (sequence "R%u", 17, 2))>;
-def CSR_Interrupts : CalleeSavedRegs<(add (sequence "R%u", 31, 0))>;
+def CSR_Interrupts : CalleeSavedRegs<(add (sequence "R%u", 31, 2))>;
diff --git a/llvm/lib/Target/AVR/AVRRegisterInfo.cpp b/llvm/lib/Target/AVR/AVRRegisterInfo.cpp
--- a/llvm/lib/Target/AVR/AVRRegisterInfo.cpp
+++ b/llvm/lib/Target/AVR/AVRRegisterInfo.cpp
@@ -45,11 +45,7 @@
 const uint32_t *
 AVRRegisterInfo::getCallPreservedMask(const MachineFunction &MF,
                                       CallingConv::ID CC) const {
-  const AVRMachineFunctionInfo *AFI = MF.getInfo<AVRMachineFunctionInfo>();
-
-  return AFI->isInterruptOrSignalHandler()
-              ? CSR_Interrupts_RegMask
-              : CSR_Normal_RegMask;
+  return CSR_Normal_RegMask;
 }
 
 BitVector AVRRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
diff --git a/llvm/test/CodeGen/AVR/interrupts.ll b/llvm/test/CodeGen/AVR/interrupts.ll
--- a/llvm/test/CodeGen/AVR/interrupts.ll
+++ b/llvm/test/CodeGen/AVR/interrupts.ll
@@ -1,5 +1,7 @@
 ; RUN: llc < %s -march=avr | FileCheck %s
 
+@count = global i8 0
+
 define avr_intrcc void @interrupt_handler() {
 ; CHECK-LABEL: interrupt_handler:
 ; CHECK: sei
@@ -104,5 +106,75 @@
   ret void
 }
 
+define void @signal_handler_with_increment() #1 {
+; CHECK-LABEL: signal_handler_with_increment:
+; CHECK:      push r0
+; CHECK-NEXT: push r1
+; CHECK-NEXT: in r0, 63
+; CHECK-NEXT: push r0
+; CHECK:      clr r0
+; CHECK-NEXT: clr r1
+; CHECK-NEXT: push r24
+; CHECK-NEXT: lds r24, count
+; CHECK-NEXT: inc r24
+; CHECK-NEXT: sts count, r24
+; CHECK-NEXT: pop r24
+; CHECK:      pop r0
+; CHECK-NEXT: out 63, r0
+; CHECK-NEXT: pop r1
+; CHECK-NEXT: pop r0
+; CHECK-NEXT: reti
+  %old = load volatile i8, i8* @count
+  %new = add i8 %old, 1
+  store volatile i8 %new, i8* @count
+  ret void
+}
+
+declare void @foo()
+
+; When a signal handler calls a function, it must push/pop all call clobbered
+; registers.
+define void @signal_handler_with_call() #1 {
+; CHECK-LABEL: signal_handler_with_call:
+; CHECK:      push r0
+; CHECK-NEXT: push r1
+; CHECK-NEXT: in r0, 63
+; CHECK-NEXT: push r0
+; CHECK:      clr r0
+; CHECK-NEXT: clr r1
+; CHECK:      push r18
+; CHECK-NEXT: push r19
+; CHECK-NEXT: push r20
+; CHECK-NEXT: push r21
+; CHECK-NEXT: push r22
+; CHECK-NEXT: push r23
+; CHECK-NEXT: push r24
+; CHECK-NEXT: push r25
+; CHECK-NEXT: push r26
+; CHECK-NEXT: push r27
+; CHECK-NEXT: push r30
+; CHECK-NEXT: push r31
+; CHECK-NEXT: call foo
+; CHECK-NEXT: pop r31
+; CHECK-NEXT: pop r30
+; CHECK-NEXT: pop r27
+; CHECK-NEXT: pop r26
+; CHECK-NEXT: pop r25
+; CHECK-NEXT: pop r24
+; CHECK-NEXT: pop r23
+; CHECK-NEXT: pop r22
+; CHECK-NEXT: pop r21
+; CHECK-NEXT: pop r20
+; CHECK-NEXT: pop r19
+; CHECK-NEXT: pop r18
+; CHECK:      pop r0
+; CHECK-NEXT: out 63, r0
+; CHECK-NEXT: pop r1
+; CHECK-NEXT: pop r0
+; CHECK-NEXT: reti
+  call void @foo()
+  ret void
+}
+
 attributes #0 = { "interrupt" }
 attributes #1 = { "signal" }