diff --git a/llvm/lib/Target/AVR/MCTargetDesc/AVRInstPrinter.cpp b/llvm/lib/Target/AVR/MCTargetDesc/AVRInstPrinter.cpp
--- a/llvm/lib/Target/AVR/MCTargetDesc/AVRInstPrinter.cpp
+++ b/llvm/lib/Target/AVR/MCTargetDesc/AVRInstPrinter.cpp
@@ -131,7 +131,7 @@
       O << getPrettyRegisterName(Op.getReg(), MRI);
     }
   } else if (Op.isImm()) {
-    O << Op.getImm();
+    O << formatImm(Op.getImm());
   } else {
     assert(Op.isExpr() && "Unknown operand kind in printOperand");
     O << *Op.getExpr();
diff --git a/llvm/test/MC/AVR/hex-immediates.s b/llvm/test/MC/AVR/hex-immediates.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/AVR/hex-immediates.s
@@ -0,0 +1,7 @@
+; RUN: llvm-mc -filetype=obj -triple=avr %s -o %t
+; RUN: llvm-objdump -d %t | FileCheck %s --check-prefix=DEC
+; RUN: llvm-objdump -d --print-imm-hex %t | FileCheck %s --check-prefix=HEX
+
+; DEC: ldi r24, 66
+; HEX: ldi r24, 0x42
+  ldi r24, 0x42