diff --git a/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp b/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
index 99fa46eb665..b55ecd6c6c2 100644
--- a/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
+++ b/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
@@ -19,6 +19,7 @@
 #include "AMDGPUTargetMachine.h"
 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
 #include "SIMachineFunctionInfo.h"
+#include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"
 #include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
 #include "llvm/CodeGen/GlobalISel/InstructionSelectorImpl.h"
 #include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"
@@ -1564,12 +1565,6 @@ AMDGPUInstructionSelector::selectFlatOffsetSigned(MachineOperand &Root) const {
   return selectFlatOffsetImpl<true>(Root);
 }
 
-// FIXME: Implement
-static bool signBitIsZero(const MachineOperand &Op,
-                          const MachineRegisterInfo &MRI) {
-  return false;
-}
-
 static bool isStackPtrRelative(const MachinePointerInfo &PtrInfo) {
   auto PSV = PtrInfo.V.dyn_cast<const PseudoSourceValue *>();
   return PSV && PSV->isStack();
@@ -1630,7 +1625,7 @@ AMDGPUInstructionSelector::selectMUBUFScratchOffen(MachineOperand &Root) const {
             RHSDef->getOperand(1).getCImm()->getSExtValue();
         if (SIInstrInfo::isLegalMUBUFImmOffset(PossibleOffset) &&
             (!STI.privateMemoryResourceIsRangeChecked() ||
-             signBitIsZero(LHS, MRI))) {
+             KnownBits->signBitIsZero(LHS.getReg()))) {
           if (LHSDef->getOpcode() == AMDGPU::G_FRAME_INDEX)
             FI = LHSDef->getOperand(1).getIndex();
           else
@@ -1680,7 +1675,7 @@ bool AMDGPUInstructionSelector::isDSOffsetLegal(const MachineRegisterInfo &MRI,
 
   // On Southern Islands instruction with a negative base value and an offset
   // don't seem to work.
-  return signBitIsZero(Base, MRI);
+  return KnownBits->signBitIsZero(Base.getReg());
 }
 
 InstructionSelector::ComplexRendererFns
diff --git a/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-local.mir b/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-local.mir
index d9a33f0cf0d..f267163206f 100644
--- a/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-local.mir
+++ b/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-local.mir
@@ -821,6 +821,51 @@ body: |
 
 ---
 
+name: load_local_s32_from_1_gep_65535_known_bits_base_address
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins:  $vgpr0
+
+    ; GFX6-LABEL: name: load_local_s32_from_1_gep_65535_known_bits_base_address
+    ; GFX6: liveins: $vgpr0
+    ; GFX6: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GFX6: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 2147483647, implicit $exec
+    ; GFX6: [[V_AND_B32_e64_:%[0-9]+]]:vgpr_32 = V_AND_B32_e64 [[COPY]], [[V_MOV_B32_e32_]], implicit $exec
+    ; GFX6: $m0 = S_MOV_B32 -1
+    ; GFX6: [[DS_READ_U8_:%[0-9]+]]:vgpr_32 = DS_READ_U8 [[V_AND_B32_e64_]], 65535, 0, implicit $m0, implicit $exec :: (load 1, addrspace 3)
+    ; GFX6: $vgpr0 = COPY [[DS_READ_U8_]]
+    ; GFX7-LABEL: name: load_local_s32_from_1_gep_65535_known_bits_base_address
+    ; GFX7: liveins: $vgpr0
+    ; GFX7: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GFX7: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 2147483647, implicit $exec
+    ; GFX7: [[V_AND_B32_e64_:%[0-9]+]]:vgpr_32 = V_AND_B32_e64 [[COPY]], [[V_MOV_B32_e32_]], implicit $exec
+    ; GFX7: $m0 = S_MOV_B32 -1
+    ; GFX7: [[DS_READ_U8_:%[0-9]+]]:vgpr_32 = DS_READ_U8 [[V_AND_B32_e64_]], 65535, 0, implicit $m0, implicit $exec :: (load 1, addrspace 3)
+    ; GFX7: $vgpr0 = COPY [[DS_READ_U8_]]
+    ; GFX9-LABEL: name: load_local_s32_from_1_gep_65535_known_bits_base_address
+    ; GFX9: liveins: $vgpr0
+    ; GFX9: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GFX9: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 2147483647, implicit $exec
+    ; GFX9: [[V_AND_B32_e64_:%[0-9]+]]:vgpr_32 = V_AND_B32_e64 [[COPY]], [[V_MOV_B32_e32_]], implicit $exec
+    ; GFX9: [[DS_READ_U8_gfx9_:%[0-9]+]]:vgpr_32 = DS_READ_U8_gfx9 [[V_AND_B32_e64_]], 65535, 0, implicit $exec :: (load 1, addrspace 3)
+    ; GFX9: $vgpr0 = COPY [[DS_READ_U8_gfx9_]]
+    %0:vgpr(s32) = COPY $vgpr0
+    %1:vgpr(s32) = G_CONSTANT i32 2147483647
+    %2:vgpr(s32) = G_AND %0, %1
+    %3:vgpr(p3) = G_INTTOPTR %2
+    %4:vgpr(s32) = G_CONSTANT i32 65535
+    %5:vgpr(p3) = G_GEP %3, %4
+    %6:vgpr(s32) = G_LOAD %5 :: (load 1, align 1, addrspace 3)
+    $vgpr0 = COPY %6
+
+...
+
+---
+
 name: load_local_s32_from_1_gep_65536
 legalized:       true
 regBankSelected: true
diff --git a/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-private.mir b/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-private.mir
index e969f457fab..dbf552433bd 100644
--- a/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-private.mir
+++ b/test/CodeGen/AMDGPU/GlobalISel/inst-select-load-private.mir
@@ -553,6 +553,46 @@ body: |
 
 ---
 
+name: load_private_s32_from_1_gep_2047_known_bits
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+machineFunctionInfo:
+  scratchRSrcReg: $sgpr0_sgpr1_sgpr2_sgpr3
+  scratchWaveOffsetReg: $sgpr4
+  stackPtrOffsetReg: $sgpr32
+
+body: |
+  bb.0:
+    liveins:  $vgpr0
+
+    ; GFX6-LABEL: name: load_private_s32_from_1_gep_2047_known_bits
+    ; GFX6: liveins: $vgpr0
+    ; GFX6: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GFX6: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 2147483647, implicit $exec
+    ; GFX6: [[V_AND_B32_e64_:%[0-9]+]]:vgpr_32 = V_AND_B32_e64 [[COPY]], [[V_MOV_B32_e32_]], implicit $exec
+    ; GFX6: [[BUFFER_LOAD_UBYTE_OFFEN:%[0-9]+]]:vgpr_32 = BUFFER_LOAD_UBYTE_OFFEN [[V_AND_B32_e64_]], $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr4, 2047, 0, 0, 0, 0, implicit $exec :: (load 1, addrspace 5)
+    ; GFX6: $vgpr0 = COPY [[BUFFER_LOAD_UBYTE_OFFEN]]
+    ; GFX9-LABEL: name: load_private_s32_from_1_gep_2047_known_bits
+    ; GFX9: liveins: $vgpr0
+    ; GFX9: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GFX9: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 2147483647, implicit $exec
+    ; GFX9: [[V_AND_B32_e64_:%[0-9]+]]:vgpr_32 = V_AND_B32_e64 [[COPY]], [[V_MOV_B32_e32_]], implicit $exec
+    ; GFX9: [[BUFFER_LOAD_UBYTE_OFFEN:%[0-9]+]]:vgpr_32 = BUFFER_LOAD_UBYTE_OFFEN [[V_AND_B32_e64_]], $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr4, 2047, 0, 0, 0, 0, implicit $exec :: (load 1, addrspace 5)
+    ; GFX9: $vgpr0 = COPY [[BUFFER_LOAD_UBYTE_OFFEN]]
+    %0:vgpr(s32) = COPY $vgpr0
+    %1:vgpr(s32) = G_CONSTANT i32 2147483647
+    %2:vgpr(s32) = G_AND %0, %1
+    %3:vgpr(p5) = G_INTTOPTR %2
+    %4:vgpr(s32) = G_CONSTANT i32 2047
+    %5:vgpr(p5) = G_GEP %3, %4
+    %6:vgpr(s32) = G_LOAD %5 :: (load 1, align 1, addrspace 5)
+    $vgpr0 = COPY %6
+
+...
+
+---
+
 name: load_private_s32_from_1_gep_2048
 legalized:       true
 regBankSelected: true