diff --git a/llvm/lib/MC/MCObjectStreamer.cpp b/llvm/lib/MC/MCObjectStreamer.cpp
--- a/llvm/lib/MC/MCObjectStreamer.cpp
+++ b/llvm/lib/MC/MCObjectStreamer.cpp
@@ -399,8 +399,7 @@
   //   fragment.
   if (Assembler.getRelaxAll() ||
       (Assembler.isBundlingEnabled() && Sec->isBundleLocked())) {
-    MCInst Relaxed;
-    getAssembler().getBackend().relaxInstruction(Inst, STI, Relaxed);
+    MCInst Relaxed = Inst;
     while (getAssembler().getBackend().mayNeedRelaxation(Relaxed, STI))
       getAssembler().getBackend().relaxInstruction(Relaxed, STI, Relaxed);
     EmitInstToData(Relaxed, STI);
diff --git a/llvm/test/MC/X86/align-branch-64-relax-all.s b/llvm/test/MC/X86/align-branch-64-relax-all.s
--- a/llvm/test/MC/X86/align-branch-64-relax-all.s
+++ b/llvm/test/MC/X86/align-branch-64-relax-all.s
@@ -1,4 +1,5 @@
   # RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu --x86-align-branch-boundary=32 --x86-align-branch=fused+jcc --mc-relax-all %s | llvm-objdump -d --no-show-raw-insn - | FileCheck %s
+  # RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu --x86-align-branch-boundary=32 --x86-align-branch=fused+jcc --x86-pad-max-prefix-size=5 --mc-relax-all %s | llvm-objdump -d --no-show-raw-insn - | FileCheck %s
 
   # Check instructions can be aligned correctly along with option --mc-relax-all