Index: llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
+++ llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
@@ -217,7 +217,12 @@
   //      BR xN
   //      barrierInsts
   Entry->addLiveIn(ThunkReg);
-  BuildMI(Entry, DebugLoc(), TII->get(AArch64::BR)).addReg(ThunkReg);
+  // MOV X16, ThunkReg == ORR X16, XZR, ThunkReg, LSL #0
+  BuildMI(Entry, DebugLoc(), TII->get(AArch64::ORRXrs), AArch64::X16)
+      .addReg(AArch64::XZR)
+      .addReg(ThunkReg)
+      .addImm(0);
+  BuildMI(Entry, DebugLoc(), TII->get(AArch64::BR)).addReg(AArch64::X16);
   // Make sure the thunks do not make use of the SB extension in case there is
   // a function somewhere that will call to it that for some reason disabled
   // the SB extension locally on that function, even though it's enabled for
Index: llvm/test/CodeGen/AArch64/speculation-hardening-sls.ll
===================================================================
--- llvm/test/CodeGen/AArch64/speculation-hardening-sls.ll
+++ llvm/test/CodeGen/AArch64/speculation-hardening-sls.ll
@@ -168,14 +168,16 @@
 }
 
 ; HARDEN-label: __llvm_slsblr_thunk_x0:
-; HARDEN:    br x0
+; HARDEN:    mov x16, x0
+; HARDEN:    br x16
 ; ISBDSB-NEXT: dsb sy
 ; ISBDSB-NEXT: isb
 ; SB-NEXT:     dsb sy
 ; SB-NEXT:     isb
 ; HARDEN-NEXT: .Lfunc_end
 ; HARDEN-label: __llvm_slsblr_thunk_x19:
-; HARDEN:    br x19
+; HARDEN:    mov x16, x19
+; HARDEN:    br x16
 ; ISBDSB-NEXT: dsb sy
 ; ISBDSB-NEXT: isb
 ; SB-NEXT:     dsb sy