diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1603,6 +1603,13 @@
       emitFrameOffset(MBB, MBBI, DL, AArch64::FP, AArch64::SP,
                       StackOffset::getFixed(FPOffset), TII,
                       MachineInstr::FrameSetup, false, NeedsWinCFI, &HasWinCFI);
+      if (NeedsWinCFI && HasWinCFI) {
+        BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_PrologEnd))
+            .setMIFlag(MachineInstr::FrameSetup);
+        // After setting up the FP, the rest of the prolog doesn't need to be
+        // included in the SEH unwind info.
+        NeedsWinCFI = false;
+      }
     }
     if (EmitCFI) {
       // Define the current CFA rule to use the provided FP.
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -4335,6 +4335,8 @@
       int Imm = (int)(ThisVal << LocalShiftSize);
       if ((DestReg == AArch64::FP && SrcReg == AArch64::SP) ||
           (SrcReg == AArch64::FP && DestReg == AArch64::SP)) {
+        if (HasWinCFI)
+          *HasWinCFI = true;
         if (Imm == 0)
           BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_SetFP)).setMIFlag(Flag);
         else
@@ -4344,16 +4346,13 @@
         assert(Offset == 0 && "Expected remaining offset to be zero to "
                               "emit a single SEH directive");
       } else if (DestReg == AArch64::SP) {
+        if (HasWinCFI)
+          *HasWinCFI = true;
         assert(SrcReg == AArch64::SP && "Unexpected SrcReg for SEH_StackAlloc");
         BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_StackAlloc))
             .addImm(Imm)
             .setMIFlag(Flag);
-      } else {
-        BuildMI(MBB, MBBI, DL, TII->get(AArch64::SEH_Nop))
-            .setMIFlag(Flag);
       }
-      if (HasWinCFI)
-        *HasWinCFI = true;
     }
 
     SrcReg = TmpReg;
diff --git a/llvm/test/CodeGen/AArch64/wineh-align-stack.ll b/llvm/test/CodeGen/AArch64/wineh-align-stack.ll
--- a/llvm/test/CodeGen/AArch64/wineh-align-stack.ll
+++ b/llvm/test/CodeGen/AArch64/wineh-align-stack.ll
@@ -17,11 +17,6 @@
 ; CHECK-NEXT: .seh_save_fplr_x 16
 ; CHECK-NEXT: mov x29, sp
 ; CHECK-NEXT: .seh_set_fp
+; CHECK-NEXT: .seh_endprologue
 ; CHECK-NEXT: sub x9, sp, #80
-; CHECK-NEXT: .seh_nop
 ; CHECK-NEXT: and sp, x9, #0xffffffffffffffe0
-; CHECK-NEXT: .seh_stackalloc 80
-; CHECK-NEXT: .seh_endprologue
-
-; FIXME: Ideally, the SEH prologue wouldn't include the stack realigning
-; instructions at all, but it's enough to end the prologue after .seh_set_fp.
diff --git a/llvm/test/CodeGen/AArch64/wineh-frame6.mir b/llvm/test/CodeGen/AArch64/wineh-frame6.mir
--- a/llvm/test/CodeGen/AArch64/wineh-frame6.mir
+++ b/llvm/test/CodeGen/AArch64/wineh-frame6.mir
@@ -7,9 +7,8 @@
 # CHECK-NEXT: frame-setup SEH_SaveFPLR_X -16
 # CHECK-NEXT: $fp = frame-setup ADDXri $sp, 0, 0
 # CHECK-NEXT: frame-setup SEH_SetFP
-# CHECK-NEXT: $sp = frame-setup SUBXri $sp, 32, 0
-# CHECK-NEXT: frame-setup SEH_StackAlloc 32
 # CHECK-NEXT: frame-setup SEH_PrologEnd
+# CHECK-NEXT: $sp = frame-setup SUBXri $sp, 32, 0
 # CHECK:      frame-destroy SEH_EpilogStart
 # CHECK-NEXT: $sp = frame-destroy ADDXri $fp, 0, 0
 # CHECK-NEXT: frame-destroy SEH_SetFP
diff --git a/llvm/test/CodeGen/AArch64/wineh-try-catch.ll b/llvm/test/CodeGen/AArch64/wineh-try-catch.ll
--- a/llvm/test/CodeGen/AArch64/wineh-try-catch.ll
+++ b/llvm/test/CodeGen/AArch64/wineh-try-catch.ll
@@ -85,8 +85,6 @@
 
 ; UNWIND: Function: ?func@@YAHXZ (0x0)
 ; UNWIND: Prologue [
-; UNWIND-NEXT: ; nop
-; UNWIND-NEXT: ; sub sp, #624
 ; UNWIND-NEXT: ; add fp, sp, #32
 ; UNWIND-NEXT: ; stp x29, x30, [sp, #32]
 ; UNWIND-NEXT: ; str x28, [sp, #24]