Index: lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
+++ lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp
@@ -32,6 +32,8 @@
     return LLT::pointer(AS, TM.getPointerSizeInBits(AS));
   };
 
+  auto AMDGPUAS = ST.getAMDGPUAS();
+
   const LLT S1 = LLT::scalar(1);
   const LLT V2S16 = LLT::vector(2, 16);
 
@@ -40,7 +42,17 @@
 
   const LLT GlobalPtr = GetAddrSpacePtr(AMDGPUAS::GLOBAL_ADDRESS);
   const LLT ConstantPtr = GetAddrSpacePtr(AMDGPUAS::CONSTANT_ADDRESS);
-
+  const LLT LocalPtr = GetAddrSpacePtr(AMDGPUAS::LOCAL_ADDRESS);
+  const LLT FlatPtr = GetAddrSpacePtr(AMDGPUAS.FLAT_ADDRESS);
+  const LLT PrivatePtr = GetAddrSpacePtr(AMDGPUAS.PRIVATE_ADDRESS);
+
+  const LLT AddrSpaces[] = {
+    GlobalPtr,
+    ConstantPtr,
+    LocalPtr,
+    FlatPtr,
+    PrivatePtr
+  };
 
   setAction({G_ADD, S32}, Legal);
   setAction({G_MUL, S32}, Legal);
@@ -84,9 +96,11 @@
   setAction({G_FPTOUI, S32}, Legal);
   setAction({G_FPTOUI, 1, S32}, Legal);
 
-  setAction({G_GEP, GlobalPtr}, Legal);
-  setAction({G_GEP, ConstantPtr}, Legal);
-  setAction({G_GEP, 1, S64}, Legal);
+  for (LLT PtrTy : AddrSpaces) {
+    LLT IdxTy = LLT::scalar(PtrTy.getSizeInBits());
+    setAction({G_GEP, PtrTy}, Legal);
+    setAction({G_GEP, 1, IdxTy}, Legal);
+  }
 
   setAction({G_ICMP, S1}, Legal);
   setAction({G_ICMP, 1, S32}, Legal);
Index: test/CodeGen/AMDGPU/GlobalISel/legalize-gep.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/GlobalISel/legalize-gep.mir
@@ -0,0 +1,92 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-mesa-mesa3d -mcpu=fiji -O0 -run-pass=legalizer -global-isel %s -o - | FileCheck %s
+
+---
+name: test_gep_global_i64_idx
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_gep_global_i64_idx
+    ; CHECK: [[COPY:%[0-9]+]]:_(p1) = COPY $vgpr0_vgpr1
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s64) = COPY $vgpr2_vgpr3
+    ; CHECK: [[GEP:%[0-9]+]]:_(p1) = G_GEP [[COPY]], [[COPY1]](s64)
+    ; CHECK: $vgpr0_vgpr1 = COPY [[GEP]](p1)
+    %0:_(p1) = COPY $vgpr0_vgpr1
+    %1:_(s64) = COPY $vgpr2_vgpr3
+    %2:_(p1) = G_GEP %0, %1
+
+    $vgpr0_vgpr1 = COPY %2
+...
+
+---
+name: test_gep_flat_i64_idx
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_gep_flat_i64_idx
+    ; CHECK: [[COPY:%[0-9]+]]:_(p0) = COPY $vgpr0_vgpr1
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s64) = COPY $vgpr2_vgpr3
+    ; CHECK: [[GEP:%[0-9]+]]:_(p0) = G_GEP [[COPY]], [[COPY1]](s64)
+    ; CHECK: $vgpr0_vgpr1 = COPY [[GEP]](p0)
+    %0:_(p0) = COPY $vgpr0_vgpr1
+    %1:_(s64) = COPY $vgpr2_vgpr3
+    %2:_(p0) = G_GEP %0, %1
+
+    $vgpr0_vgpr1 = COPY %2
+...
+
+---
+name: test_gep_constant_i64_idx
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1, $vgpr2_vgpr3
+
+    ; CHECK-LABEL: name: test_gep_constant_i64_idx
+    ; CHECK: [[COPY:%[0-9]+]]:_(p4) = COPY $vgpr0_vgpr1
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s64) = COPY $vgpr2_vgpr3
+    ; CHECK: [[GEP:%[0-9]+]]:_(p4) = G_GEP [[COPY]], [[COPY1]](s64)
+    ; CHECK: $vgpr0_vgpr1 = COPY [[GEP]](p4)
+    %0:_(p4) = COPY $vgpr0_vgpr1
+    %1:_(s64) = COPY $vgpr2_vgpr3
+    %2:_(p4) = G_GEP %0, %1
+
+    $vgpr0_vgpr1 = COPY %2
+...
+
+---
+name: test_gep_local_i32_idx
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: test_gep_local_i32_idx
+    ; CHECK: [[COPY:%[0-9]+]]:_(p3) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[GEP:%[0-9]+]]:_(p3) = G_GEP [[COPY]], [[COPY1]](s32)
+    ; CHECK: $vgpr0 = COPY [[GEP]](p3)
+    %0:_(p3) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(p3) = G_GEP %0, %1
+
+    $vgpr0 = COPY %2
+...
+
+---
+name: test_gep_private_i32_idx
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: test_gep_private_i32_idx
+    ; CHECK: [[COPY:%[0-9]+]]:_(p5) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[GEP:%[0-9]+]]:_(p5) = G_GEP [[COPY]], [[COPY1]](s32)
+    ; CHECK: $vgpr0 = COPY [[GEP]](p5)
+    %0:_(p5) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(p5) = G_GEP %0, %1
+
+    $vgpr0 = COPY %2
+...