Index: llvm/include/llvm/CodeGen/IndirectThunks.h
===================================================================
--- llvm/include/llvm/CodeGen/IndirectThunks.h
+++ llvm/include/llvm/CodeGen/IndirectThunks.h
@@ -100,7 +100,7 @@
     if (!getDerived().mayUseThunk(MF))
       return false;
 
-    getDerived().insertThunks(MMI);
+    getDerived().insertThunks(MMI, MF);
     InsertedThunks = true;
     return true;
   }
Index: llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
+++ llvm/lib/Target/AArch64/AArch64SLSHardening.cpp
@@ -191,7 +191,7 @@
     // to more accurately reflect if a thunk will be needed.
     return MF.getSubtarget<AArch64Subtarget>().hardenSlsBlr();
   }
-  void insertThunks(MachineModuleInfo &MMI);
+  void insertThunks(MachineModuleInfo &MMI, MachineFunction &MF);
   void populateThunk(MachineFunction &MF);
 
 private:
@@ -199,7 +199,7 @@
 };
 } // namespace
 
-void SLSBLRThunkInserter::insertThunks(MachineModuleInfo &MMI) {
+void SLSBLRThunkInserter::insertThunks(MachineModuleInfo &MMI, MachineFunction &MF) {
   // FIXME: It probably would be possible to filter which thunks to produce
   // based on which registers are actually used in BLR instructions in this
   // function. But would that be a worthwhile optimization?
Index: llvm/lib/Target/ARM/ARMSLSHardening.cpp
===================================================================
--- llvm/lib/Target/ARM/ARMSLSHardening.cpp
+++ llvm/lib/Target/ARM/ARMSLSHardening.cpp
@@ -170,7 +170,7 @@
     // function to more accurately reflect if a thunk will be needed.
     return MF.getSubtarget<ARMSubtarget>().hardenSlsBlr();
   }
-  void insertThunks(MachineModuleInfo &MMI);
+  void insertThunks(MachineModuleInfo &MMI, MachineFunction &MF);
   void populateThunk(MachineFunction &MF);
 
 private:
@@ -178,12 +178,14 @@
 };
 } // namespace
 
-void SLSBLRThunkInserter::insertThunks(MachineModuleInfo &MMI) {
+void SLSBLRThunkInserter::insertThunks(MachineModuleInfo &MMI, MachineFunction &MF) {
   // FIXME: It probably would be possible to filter which thunks to produce
   // based on which registers are actually used in indirect calls in this
   // function. But would that be a worthwhile optimization?
+  const ARMSubtarget *ST = &MF.getSubtarget<ARMSubtarget>();
   for (auto T : SLSBLRThunks)
-    createThunkFunction(MMI, T.Name, ComdatThunks);
+    if (ST->isThumb() == T.isThumb)
+      createThunkFunction(MMI, T.Name, ComdatThunks);
 }
 
 void SLSBLRThunkInserter::populateThunk(MachineFunction &MF) {
Index: llvm/lib/Target/X86/X86IndirectThunks.cpp
===================================================================
--- llvm/lib/Target/X86/X86IndirectThunks.cpp
+++ llvm/lib/Target/X86/X86IndirectThunks.cpp
@@ -67,7 +67,7 @@
             STI.useRetpolineIndirectBranches()) &&
            !STI.useRetpolineExternalThunk();
   }
-  void insertThunks(MachineModuleInfo &MMI);
+  void insertThunks(MachineModuleInfo &MMI, MachineFunction &MF);
   void populateThunk(MachineFunction &MF);
 };
 
@@ -76,7 +76,7 @@
   bool mayUseThunk(const MachineFunction &MF) {
     return MF.getSubtarget<X86Subtarget>().useLVIControlFlowIntegrity();
   }
-  void insertThunks(MachineModuleInfo &MMI) {
+  void insertThunks(MachineModuleInfo &MMI, MachineFunction &MF) {
     createThunkFunction(MMI, R11LVIThunkName);
   }
   void populateThunk(MachineFunction &MF) {
@@ -132,7 +132,7 @@
 
 } // end anonymous namespace
 
-void RetpolineThunkInserter::insertThunks(MachineModuleInfo &MMI) {
+void RetpolineThunkInserter::insertThunks(MachineModuleInfo &MMI, MachineFunction &MF) {
   if (MMI.getTarget().getTargetTriple().getArch() == Triple::x86_64)
     createThunkFunction(MMI, R11RetpolineName);
   else
Index: llvm/test/CodeGen/ARM/speculation-hardening-sls.ll
===================================================================
--- llvm/test/CodeGen/ARM/speculation-hardening-sls.ll
+++ llvm/test/CodeGen/ARM/speculation-hardening-sls.ll
@@ -259,4 +259,5 @@
 ; SB-NEXT:     isb
 ; HARDEN-NEXT: .Lfunc_end
 
-
+; THUMB-NOT: __llvm_slsblr_thunk_arm
+; ARM-NOT: __llvm_slsblr_thunk_thumb