Index: llvm/lib/CodeGen/PrologEpilogInserter.cpp
===================================================================
--- llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -1273,9 +1273,10 @@
     }
   }
 
-  // Don't clear registers that are reset before exiting.
-  for (const CalleeSavedInfo &CSI : MF.getFrameInfo().getCalleeSavedInfo())
-    for (MCRegister Reg : TRI.sub_and_superregs_inclusive(CSI.getReg()))
+  // Don't clear registers that must be preserved.
+  for (const MCPhysReg *CSRegs = TRI.getCalleeSavedRegs(&MF);
+       MCPhysReg CSReg = *CSRegs; ++CSRegs)
+    for (MCRegister Reg : TRI.sub_and_superregs_inclusive(CSReg))
       RegsToZero.reset(Reg);
 
   const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
Index: llvm/test/CodeGen/AArch64/zero-call-used-regs.ll
===================================================================
--- llvm/test/CodeGen/AArch64/zero-call-used-regs.ll
+++ llvm/test/CodeGen/AArch64/zero-call-used-regs.ll
@@ -220,14 +220,6 @@
 ; DEFAULT-NEXT:    movi v5.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v6.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v7.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v8.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v9.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v10.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v11.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v12.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v13.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v14.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v15.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v16.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v17.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v18.2d, #0000000000000000
@@ -276,14 +268,6 @@
 ; SVE-NEXT:    mov z5.d, #0 // =0x0
 ; SVE-NEXT:    mov z6.d, #0 // =0x0
 ; SVE-NEXT:    mov z7.d, #0 // =0x0
-; SVE-NEXT:    mov z8.d, #0 // =0x0
-; SVE-NEXT:    mov z9.d, #0 // =0x0
-; SVE-NEXT:    mov z10.d, #0 // =0x0
-; SVE-NEXT:    mov z11.d, #0 // =0x0
-; SVE-NEXT:    mov z12.d, #0 // =0x0
-; SVE-NEXT:    mov z13.d, #0 // =0x0
-; SVE-NEXT:    mov z14.d, #0 // =0x0
-; SVE-NEXT:    mov z15.d, #0 // =0x0
 ; SVE-NEXT:    mov z16.d, #0 // =0x0
 ; SVE-NEXT:    mov z17.d, #0 // =0x0
 ; SVE-NEXT:    mov z18.d, #0 // =0x0
@@ -548,14 +532,6 @@
 ; DEFAULT-NEXT:    movi v5.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v6.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v7.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v8.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v9.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v10.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v11.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v12.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v13.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v14.2d, #0000000000000000
-; DEFAULT-NEXT:    movi v15.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v16.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v17.2d, #0000000000000000
 ; DEFAULT-NEXT:    movi v18.2d, #0000000000000000
@@ -604,14 +580,6 @@
 ; SVE-NEXT:    mov z5.d, #0 // =0x0
 ; SVE-NEXT:    mov z6.d, #0 // =0x0
 ; SVE-NEXT:    mov z7.d, #0 // =0x0
-; SVE-NEXT:    mov z8.d, #0 // =0x0
-; SVE-NEXT:    mov z9.d, #0 // =0x0
-; SVE-NEXT:    mov z10.d, #0 // =0x0
-; SVE-NEXT:    mov z11.d, #0 // =0x0
-; SVE-NEXT:    mov z12.d, #0 // =0x0
-; SVE-NEXT:    mov z13.d, #0 // =0x0
-; SVE-NEXT:    mov z14.d, #0 // =0x0
-; SVE-NEXT:    mov z15.d, #0 // =0x0
 ; SVE-NEXT:    mov z16.d, #0 // =0x0
 ; SVE-NEXT:    mov z17.d, #0 // =0x0
 ; SVE-NEXT:    mov z18.d, #0 // =0x0
Index: llvm/test/CodeGen/X86/zero-call-used-regs.ll
===================================================================
--- llvm/test/CodeGen/X86/zero-call-used-regs.ll
+++ llvm/test/CodeGen/X86/zero-call-used-regs.ll
@@ -110,19 +110,13 @@
 ; I386-LABEL: all_gpr:
 ; I386:       # %bb.0: # %entry
 ; I386-NEXT:    movl {{[0-9]+}}(%esp), %eax
-; I386-NEXT:    xorl %ebp, %ebp
-; I386-NEXT:    xorl %ebx, %ebx
 ; I386-NEXT:    xorl %ecx, %ecx
-; I386-NEXT:    xorl %edi, %edi
 ; I386-NEXT:    xorl %edx, %edx
-; I386-NEXT:    xorl %esi, %esi
 ; I386-NEXT:    retl
 ;
 ; X86-64-LABEL: all_gpr:
 ; X86-64:       # %bb.0: # %entry
 ; X86-64-NEXT:    movl %edi, %eax
-; X86-64-NEXT:    xorl %ebp, %ebp
-; X86-64-NEXT:    xorl %ebx, %ebx
 ; X86-64-NEXT:    xorl %ecx, %ecx
 ; X86-64-NEXT:    xorl %edi, %edi
 ; X86-64-NEXT:    xorl %edx, %edx
@@ -131,10 +125,6 @@
 ; X86-64-NEXT:    xorl %r9d, %r9d
 ; X86-64-NEXT:    xorl %r10d, %r10d
 ; X86-64-NEXT:    xorl %r11d, %r11d
-; X86-64-NEXT:    xorl %r12d, %r12d
-; X86-64-NEXT:    xorl %r13d, %r13d
-; X86-64-NEXT:    xorl %r14d, %r14d
-; X86-64-NEXT:    xorl %r15d, %r15d
 ; X86-64-NEXT:    retq
 
 entry:
@@ -190,12 +180,8 @@
 ; I386-NEXT:    fstp %st(0)
 ; I386-NEXT:    fstp %st(0)
 ; I386-NEXT:    fstp %st(0)
-; I386-NEXT:    xorl %ebp, %ebp
-; I386-NEXT:    xorl %ebx, %ebx
 ; I386-NEXT:    xorl %ecx, %ecx
-; I386-NEXT:    xorl %edi, %edi
 ; I386-NEXT:    xorl %edx, %edx
-; I386-NEXT:    xorl %esi, %esi
 ; I386-NEXT:    xorps %xmm0, %xmm0
 ; I386-NEXT:    xorps %xmm1, %xmm1
 ; I386-NEXT:    xorps %xmm2, %xmm2
@@ -225,8 +211,6 @@
 ; X86-64-NEXT:    fstp %st(0)
 ; X86-64-NEXT:    fstp %st(0)
 ; X86-64-NEXT:    fstp %st(0)
-; X86-64-NEXT:    xorl %ebp, %ebp
-; X86-64-NEXT:    xorl %ebx, %ebx
 ; X86-64-NEXT:    xorl %ecx, %ecx
 ; X86-64-NEXT:    xorl %edi, %edi
 ; X86-64-NEXT:    xorl %edx, %edx
@@ -235,10 +219,6 @@
 ; X86-64-NEXT:    xorl %r9d, %r9d
 ; X86-64-NEXT:    xorl %r10d, %r10d
 ; X86-64-NEXT:    xorl %r11d, %r11d
-; X86-64-NEXT:    xorl %r12d, %r12d
-; X86-64-NEXT:    xorl %r13d, %r13d
-; X86-64-NEXT:    xorl %r14d, %r14d
-; X86-64-NEXT:    xorl %r15d, %r15d
 ; X86-64-NEXT:    xorps %xmm0, %xmm0
 ; X86-64-NEXT:    xorps %xmm1, %xmm1
 ; X86-64-NEXT:    xorps %xmm2, %xmm2