Index: llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.h
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.h
+++ llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.h
@@ -40,8 +40,8 @@
   int getFrameIndexReference(const MachineFunction &MF, int FI,
                              unsigned &FrameReg) const override;
   int resolveFrameIndexReference(const MachineFunction &MF, int FI,
-                                 unsigned &FrameReg,
-                                 bool PreferFP = false) const;
+                                 unsigned &FrameReg, bool PreferFP,
+                                 bool ForSimm) const;
   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI,
Index: llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -1497,7 +1497,11 @@
 int AArch64FrameLowering::getFrameIndexReference(const MachineFunction &MF,
                                                  int FI,
                                                  unsigned &FrameReg) const {
-  return resolveFrameIndexReference(MF, FI, FrameReg);
+  return resolveFrameIndexReference(
+      MF, FI, FrameReg,
+      /*PreferFP=*/
+      MF.getFunction().hasFnAttribute(Attribute::SanitizeHWAddress),
+      /*ForSimm=*/false);
 }
 
 int AArch64FrameLowering::getNonLocalFrameIndexReference(
@@ -1530,7 +1534,8 @@
 
 int AArch64FrameLowering::resolveFrameIndexReference(const MachineFunction &MF,
                                                      int FI, unsigned &FrameReg,
-                                                     bool PreferFP) const {
+                                                     bool PreferFP,
+                                                     bool ForSimm) const {
   const auto &MFI = MF.getFrameInfo();
   const auto *RegInfo = static_cast<const AArch64RegisterInfo *>(
       MF.getSubtarget().getRegisterInfo());
@@ -1561,11 +1566,11 @@
       assert(hasFP(MF) && "Re-aligned stack must have frame pointer");
       UseFP = true;
     } else if (hasFP(MF) && !RegInfo->needsStackRealignment(MF)) {
-      // If the FPOffset is negative, we have to keep in mind that the
-      // available offset range for negative offsets is smaller than for
-      // positive ones. If an offset is
-      // available via the FP and the SP, use whichever is closest.
-      bool FPOffsetFits = FPOffset >= -256;
+      // If the FPOffset is negative and we're producing a signed immediate, we
+      // have to keep in mind that the available offset range for negative
+      // offsets is smaller than for positive ones. If an offset is available
+      // via the FP and the SP, use whichever is closest.
+      bool FPOffsetFits = !ForSimm || FPOffset >= -256;
       PreferFP |= Offset > -FPOffset;
 
       if (MFI.hasVarSizedObjects()) {
Index: llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
===================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
+++ llvm/trunk/lib/Target/AArch64/AArch64RegisterInfo.cpp
@@ -453,7 +453,8 @@
   if (MI.isDebugValue() || MI.getOpcode() == TargetOpcode::STACKMAP ||
       MI.getOpcode() == TargetOpcode::PATCHPOINT) {
     Offset = TFI->resolveFrameIndexReference(MF, FrameIndex, FrameReg,
-                                             /*PreferFP=*/true);
+                                             /*PreferFP=*/true,
+                                             /*ForSimm=*/false);
     Offset += MI.getOperand(FIOperandNum + 1).getImm();
     MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false /*isDef*/);
     MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
@@ -468,7 +469,8 @@
   }
 
   // Modify MI as necessary to handle as much of 'Offset' as possible
-  Offset = TFI->getFrameIndexReference(MF, FrameIndex, FrameReg);
+  Offset = TFI->resolveFrameIndexReference(
+      MF, FrameIndex, FrameReg, /*PreferFP=*/false, /*ForSimm=*/true);
 
   if (rewriteAArch64FrameIndex(MI, FIOperandNum, FrameReg, Offset, TII))
     return;
Index: llvm/trunk/test/CodeGen/AArch64/hwasan-prefer-fp.ll
===================================================================
--- llvm/trunk/test/CodeGen/AArch64/hwasan-prefer-fp.ll
+++ llvm/trunk/test/CodeGen/AArch64/hwasan-prefer-fp.ll
@@ -0,0 +1,41 @@
+; RUN: llc -o - %s -filetype=obj -frame-pointer=all | llvm-dwarfdump - | FileCheck %s
+
+target triple="aarch64--"
+
+define void @f() sanitize_hwaddress !dbg !6 {
+entry:
+  %x = call i8* @g(i32 0)
+  %a = alloca [128 x i8]
+  %b = alloca [128 x i8]
+  ; CHECK: DW_AT_location (DW_OP_fbreg
+  call void @llvm.dbg.declare(metadata [128 x i8]* %a, metadata !12, metadata !DIExpression()), !dbg !14
+  ; CHECK: DW_AT_location (DW_OP_fbreg
+  call void @llvm.dbg.declare(metadata [128 x i8]* %b, metadata !13, metadata !DIExpression()), !dbg !14
+  ret void, !dbg !15
+}
+
+declare i8* @g(i32)
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "x.c", directory: "/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang"}
+!6 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags:
+DIFlagPrototyped, isOptimized: false, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{null, !9}
+!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
+!10 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !11)
+!11 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!12 = !DILocalVariable(name: "a", scope: !6, file: !1, line: 1, type: !9)
+!13 = !DILocalVariable(name: "b", scope: !6, file: !1, line: 1, type: !9)
+!14 = !DILocation(line: 1, column: 29, scope: !6)
+!15 = !DILocation(line: 1, column: 37, scope: !6)