diff --git a/llvm/lib/Target/AVR/AVRAsmPrinter.cpp b/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
--- a/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
+++ b/llvm/lib/Target/AVR/AVRAsmPrinter.cpp
@@ -128,8 +128,8 @@
       assert(BytesPerReg <= 2 && "Only 8 and 16 bit regs are supported.");
 
       unsigned RegIdx = ByteNumber / BytesPerReg;
-      assert(RegIdx < NumOpRegs && "Multibyte index out of range.");
-
+      if (RegIdx >= NumOpRegs)
+        return true;
       Reg = MI->getOperand(OpNum + RegIdx).getReg();
 
       if (BytesPerReg == 2) {
diff --git a/llvm/test/CodeGen/AVR/inline-asm/inline-asm-invalid.ll b/llvm/test/CodeGen/AVR/inline-asm/inline-asm-invalid.ll
--- a/llvm/test/CodeGen/AVR/inline-asm/inline-asm-invalid.ll
+++ b/llvm/test/CodeGen/AVR/inline-asm/inline-asm-invalid.ll
@@ -8,3 +8,8 @@
   ret void
 }
 
+define void @foo1() {
+  ; CHECK: error: invalid operand in inline asm: ';; ${0:C}'
+  call i16 asm sideeffect ";; ${0:C}", "=d"()
+  ret void
+}