Index: lib/Target/AArch64/AArch64BranchRelaxation.cpp
===================================================================
--- lib/Target/AArch64/AArch64BranchRelaxation.cpp
+++ lib/Target/AArch64/AArch64BranchRelaxation.cpp
@@ -426,7 +426,9 @@
     // Analyze the branch so we know how to update the successor lists.
     MachineBasicBlock *TBB, *FBB;
     SmallVector<MachineOperand, 2> Cond;
-    TII->analyzeBranch(*MBB, TBB, FBB, Cond, false);
+    bool Fail = TII->analyzeBranch(*MBB, TBB, FBB, Cond, false);
+    assert(!Fail && "branches to relax should be analyzable");
+    (void)Fail;
 
     MachineBasicBlock *NewBB = splitBlockBeforeInstr(MI);
     // No need for the branch to the next block. We're adding an unconditional