diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerModuleLDSPass.cpp
@@ -172,6 +172,18 @@
       return false;
     }
 
+    // Go through each LDS, and if it is under-aligned, then find its natural
+    // alignment, and update it accordingly. This is will make sure that the
+    // members of sorted structure are properly aligned, and hence it will
+    // further reduce the probability of unaligned LDS access.
+    for (auto *GV : FoundLocalVars) {
+      Align Alignment = AMDGPU::getAlign(DL, GV);
+      Align FixedAlignment = AMDGPU::fixAlignment(GV, Alignment, DL);
+      if (Alignment != FixedAlignment) {
+        GV->setAlignment(FixedAlignment);
+      }
+    }
+
     // Sort by alignment, descending, to minimise padding.
     // On ties, sort by size, descending, then by name, lexicographical.
     llvm::stable_sort(
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.h
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.h
@@ -42,6 +42,10 @@
 /// \returns true if all uses of \p U end up in a function \p F.
 bool isUsedOnlyFromFunction(const User *U, const Function *F);
 
+// Fix natural alignment for LDS global `GV` based on its size.
+Align fixAlignment(const GlobalVariable *GV, Align Alignment,
+                   const DataLayout &DL);
+
 } // end namespace AMDGPU
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.cpp b/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.cpp
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.cpp
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPULDSUtils.cpp
@@ -149,6 +149,28 @@
   return UsedList;
 }
 
+// Fix natural alignment for LDS global `GV` based on its size.
+Align fixAlignment(const GlobalVariable *GV, Align Alignment,
+                   const DataLayout &DL) {
+  TypeSize GVSize = DL.getTypeAllocSize(GV->getValueType());
+
+  if (GVSize > 8) {
+    // We might want to use a b96 or b128 load/store
+    Alignment = std::max(Alignment, Align(16));
+  } else if (GVSize > 4) {
+    // We might want to use a b64 load/store
+    Alignment = std::max(Alignment, Align(8));
+  } else if (GVSize > 2) {
+    // We might want to use a b32 load/store
+    Alignment = std::max(Alignment, Align(4));
+  } else if (GVSize > 1) {
+    // We might want to use a b16 load/store
+    Alignment = std::max(Alignment, Align(2));
+  }
+
+  return Alignment;
+}
+
 } // end namespace AMDGPU
 
 } // end namespace llvm
diff --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/lds-global-value.ll b/llvm/test/CodeGen/AMDGPU/GlobalISel/lds-global-value.ll
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/lds-global-value.ll
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/lds-global-value.ll
@@ -9,7 +9,7 @@
 ; CHECK-LABEL: use_lds_globals:
 ; CHECK:       ; %bb.0: ; %entry
 ; CHECK-NEXT:    s_load_dwordx2 s[0:1], s[4:5], 0x0
-; CHECK-NEXT:    v_mov_b32_e32 v0, 8
+; CHECK-NEXT:    v_mov_b32_e32 v0, 4
 ; CHECK-NEXT:    s_mov_b32 m0, -1
 ; CHECK-NEXT:    ds_read_b32 v3, v0
 ; CHECK-NEXT:    v_mov_b32_e32 v2, 9
@@ -19,7 +19,7 @@
 ; CHECK-NEXT:    v_mov_b32_e32 v0, s0
 ; CHECK-NEXT:    v_mov_b32_e32 v1, s1
 ; CHECK-NEXT:    flat_store_dword v[0:1], v3
-; CHECK-NEXT:    v_mov_b32_e32 v0, 0
+; CHECK-NEXT:    v_mov_b32_e32 v0, 0x200
 ; CHECK-NEXT:    ds_write_b32 v0, v2
 ; CHECK-NEXT:    s_endpgm
 entry:
diff --git a/llvm/test/CodeGen/AMDGPU/ds_read2.ll b/llvm/test/CodeGen/AMDGPU/ds_read2.ll
--- a/llvm/test/CodeGen/AMDGPU/ds_read2.ll
+++ b/llvm/test/CodeGen/AMDGPU/ds_read2.ll
@@ -1007,10 +1007,9 @@
 define amdgpu_kernel void @load_misaligned64_constant_offsets(i64 addrspace(1)* %out) {
 ; CI-LABEL: load_misaligned64_constant_offsets:
 ; CI:       ; %bb.0:
-; CI-NEXT:    v_mov_b32_e32 v2, 0
+; CI-NEXT:    v_mov_b32_e32 v0, 0
 ; CI-NEXT:    s_mov_b32 m0, -1
-; CI-NEXT:    ds_read2_b32 v[0:1], v2 offset1:1
-; CI-NEXT:    ds_read2_b32 v[2:3], v2 offset0:2 offset1:3
+; CI-NEXT:    ds_read2_b64 v[0:3], v0 offset1:1
 ; CI-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x9
 ; CI-NEXT:    s_mov_b32 s3, 0xf000
 ; CI-NEXT:    s_mov_b32 s2, -1
@@ -1023,8 +1022,7 @@
 ; GFX9-ALIGNED-LABEL: load_misaligned64_constant_offsets:
 ; GFX9-ALIGNED:       ; %bb.0:
 ; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v4, 0
-; GFX9-ALIGNED-NEXT:    ds_read2_b32 v[0:1], v4 offset1:1
-; GFX9-ALIGNED-NEXT:    ds_read2_b32 v[2:3], v4 offset0:2 offset1:3
+; GFX9-ALIGNED-NEXT:    ds_read2_b64 v[0:3], v4 offset1:1
 ; GFX9-ALIGNED-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x24
 ; GFX9-ALIGNED-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX9-ALIGNED-NEXT:    v_add_co_u32_e32 v0, vcc, v0, v2
@@ -1035,7 +1033,7 @@
 ; GFX9-UNALIGNED-LABEL: load_misaligned64_constant_offsets:
 ; GFX9-UNALIGNED:       ; %bb.0:
 ; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v4, 0
-; GFX9-UNALIGNED-NEXT:    ds_read2_b64 v[0:3], v4 offset1:1
+; GFX9-UNALIGNED-NEXT:    ds_read_b128 v[0:3], v4
 ; GFX9-UNALIGNED-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x24
 ; GFX9-UNALIGNED-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX9-UNALIGNED-NEXT:    v_add_co_u32_e32 v0, vcc, v0, v2
@@ -1054,11 +1052,10 @@
 define amdgpu_kernel void @load_misaligned64_constant_large_offsets(i64 addrspace(1)* %out) {
 ; CI-LABEL: load_misaligned64_constant_large_offsets:
 ; CI:       ; %bb.0:
-; CI-NEXT:    v_mov_b32_e32 v0, 0x4000
-; CI-NEXT:    v_mov_b32_e32 v2, 0x7ff8
+; CI-NEXT:    v_mov_b32_e32 v2, 0
 ; CI-NEXT:    s_mov_b32 m0, -1
-; CI-NEXT:    ds_read2_b32 v[0:1], v0 offset1:1
-; CI-NEXT:    ds_read2_b32 v[2:3], v2 offset1:1
+; CI-NEXT:    ds_read_b64 v[0:1], v2 offset:16384
+; CI-NEXT:    ds_read_b64 v[2:3], v2 offset:32760
 ; CI-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x9
 ; CI-NEXT:    s_mov_b32 s3, 0xf000
 ; CI-NEXT:    s_mov_b32 s2, -1
@@ -1070,12 +1067,10 @@
 ;
 ; GFX9-LABEL: load_misaligned64_constant_large_offsets:
 ; GFX9:       ; %bb.0:
-; GFX9-NEXT:    v_mov_b32_e32 v0, 0x4000
-; GFX9-NEXT:    v_mov_b32_e32 v2, 0x7ff8
-; GFX9-NEXT:    ds_read2_b32 v[0:1], v0 offset1:1
-; GFX9-NEXT:    ds_read2_b32 v[2:3], v2 offset1:1
-; GFX9-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x24
 ; GFX9-NEXT:    v_mov_b32_e32 v4, 0
+; GFX9-NEXT:    ds_read_b64 v[0:1], v4 offset:16384
+; GFX9-NEXT:    ds_read_b64 v[2:3], v4 offset:32760
+; GFX9-NEXT:    s_load_dwordx2 s[0:1], s[0:1], 0x24
 ; GFX9-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX9-NEXT:    v_add_co_u32_e32 v0, vcc, v0, v2
 ; GFX9-NEXT:    v_addc_co_u32_e32 v1, vcc, v1, v3, vcc
diff --git a/llvm/test/CodeGen/AMDGPU/ds_read2_offset_order.ll b/llvm/test/CodeGen/AMDGPU/ds_read2_offset_order.ll
--- a/llvm/test/CodeGen/AMDGPU/ds_read2_offset_order.ll
+++ b/llvm/test/CodeGen/AMDGPU/ds_read2_offset_order.ll
@@ -6,10 +6,10 @@
 ; offset0 is larger than offset1
 
 ; SI-LABEL: {{^}}offset_order:
-; SI-DAG: ds_read2_b32 v[{{[0-9]+}}:{{[0-9]+}}], v{{[0-9]+}} offset1:14{{$}}
-; SI-DAG: ds_read2_b32 v[{{[0-9]+}}:{{[0-9]+}}], v{{[0-9]+}} offset0:2 offset1:3
-; SI-DAG: ds_read_b32 v{{[0-9]+}}, v{{[0-9]+}} offset:1024
+; SI-DAG: ds_read_b32 v{{[0-9]+}}, v{{[0-9]+}}
+; SI-DAG: ds_read_b64 v[{{[0-9]+}}:{{[0-9]+}}], v{{[0-9]+}} offset:8
 ; SI-DAG: ds_read2_b32 v[{{[0-9]+}}:{{[0-9]+}}], v{{[0-9]+}} offset0:11 offset1:12
+; SI-DAG: ds_read2_b32 v[{{[0-9]+}}:{{[0-9]+}}], v{{[0-9]+}} offset0:6 offset1:248
 define amdgpu_kernel void @offset_order(float addrspace(1)* %out) {
 entry:
   %ptr0 = getelementptr inbounds [512 x float], [512 x float] addrspace(3)* @lds, i32 0, i32 0
diff --git a/llvm/test/CodeGen/AMDGPU/ds_write2.ll b/llvm/test/CodeGen/AMDGPU/ds_write2.ll
--- a/llvm/test/CodeGen/AMDGPU/ds_write2.ll
+++ b/llvm/test/CodeGen/AMDGPU/ds_write2.ll
@@ -820,33 +820,32 @@
 define amdgpu_kernel void @store_misaligned64_constant_offsets() {
 ; CI-LABEL: store_misaligned64_constant_offsets:
 ; CI:       ; %bb.0:
-; CI-NEXT:    v_mov_b32_e32 v0, 0
-; CI-NEXT:    v_mov_b32_e32 v1, 0x7b
+; CI-NEXT:    s_movk_i32 s0, 0x7b
+; CI-NEXT:    s_mov_b32 s1, 0
+; CI-NEXT:    v_mov_b32_e32 v0, s0
+; CI-NEXT:    v_mov_b32_e32 v2, 0
+; CI-NEXT:    v_mov_b32_e32 v1, s1
 ; CI-NEXT:    s_mov_b32 m0, -1
-; CI-NEXT:    ds_write2_b32 v0, v1, v0 offset1:1
-; CI-NEXT:    ds_write2_b32 v0, v1, v0 offset0:2 offset1:3
+; CI-NEXT:    ds_write2_b64 v2, v[0:1], v[0:1] offset1:1
 ; CI-NEXT:    s_endpgm
 ;
 ; GFX9-ALIGNED-LABEL: store_misaligned64_constant_offsets:
 ; GFX9-ALIGNED:       ; %bb.0:
-; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v0, 0
-; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v1, 0x7b
-; GFX9-ALIGNED-NEXT:    ds_write2_b32 v0, v1, v0 offset1:1
-; GFX9-ALIGNED-NEXT:    ds_write2_b32 v0, v1, v0 offset0:2 offset1:3
+; GFX9-ALIGNED-NEXT:    s_movk_i32 s0, 0x7b
+; GFX9-ALIGNED-NEXT:    s_mov_b32 s1, 0
+; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v0, s0
+; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v2, 0
+; GFX9-ALIGNED-NEXT:    v_mov_b32_e32 v1, s1
+; GFX9-ALIGNED-NEXT:    ds_write2_b64 v2, v[0:1], v[0:1] offset1:1
 ; GFX9-ALIGNED-NEXT:    s_endpgm
 ;
 ; GFX9-UNALIGNED-LABEL: store_misaligned64_constant_offsets:
 ; GFX9-UNALIGNED:       ; %bb.0:
-; GFX9-UNALIGNED-NEXT:    s_movk_i32 s0, 0x7b
-; GFX9-UNALIGNED-NEXT:    s_mov_b32 s1, 0
-; GFX9-UNALIGNED-NEXT:    s_mov_b32 s2, s0
-; GFX9-UNALIGNED-NEXT:    s_mov_b32 s3, s1
-; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v0, s0
-; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v2, s2
-; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v4, 0
-; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v1, s1
-; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v3, s3
-; GFX9-UNALIGNED-NEXT:    ds_write2_b64 v4, v[0:1], v[2:3] offset1:1
+; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v0, 0x7b
+; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v1, 0
+; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v2, v0
+; GFX9-UNALIGNED-NEXT:    v_mov_b32_e32 v3, v1
+; GFX9-UNALIGNED-NEXT:    ds_write_b128 v1, v[0:3]
 ; GFX9-UNALIGNED-NEXT:    s_endpgm
   store i64 123, i64 addrspace(3)* getelementptr inbounds ([4 x i64], [4 x i64] addrspace(3)* @bar, i32 0, i32 0), align 4
   store i64 123, i64 addrspace(3)* getelementptr inbounds ([4 x i64], [4 x i64] addrspace(3)* @bar, i32 0, i32 1), align 4
@@ -858,23 +857,25 @@
 define amdgpu_kernel void @store_misaligned64_constant_large_offsets() {
 ; CI-LABEL: store_misaligned64_constant_large_offsets:
 ; CI:       ; %bb.0:
-; CI-NEXT:    v_mov_b32_e32 v0, 0x4000
-; CI-NEXT:    v_mov_b32_e32 v1, 0x7b
+; CI-NEXT:    s_movk_i32 s0, 0x7b
+; CI-NEXT:    s_mov_b32 s1, 0
+; CI-NEXT:    v_mov_b32_e32 v0, s0
 ; CI-NEXT:    v_mov_b32_e32 v2, 0
+; CI-NEXT:    v_mov_b32_e32 v1, s1
 ; CI-NEXT:    s_mov_b32 m0, -1
-; CI-NEXT:    ds_write2_b32 v0, v1, v2 offset1:1
-; CI-NEXT:    v_mov_b32_e32 v0, 0x7ff8
-; CI-NEXT:    ds_write2_b32 v0, v1, v2 offset1:1
+; CI-NEXT:    ds_write_b64 v2, v[0:1] offset:16384
+; CI-NEXT:    ds_write_b64 v2, v[0:1] offset:32760
 ; CI-NEXT:    s_endpgm
 ;
 ; GFX9-LABEL: store_misaligned64_constant_large_offsets:
 ; GFX9:       ; %bb.0:
-; GFX9-NEXT:    v_mov_b32_e32 v0, 0x4000
-; GFX9-NEXT:    v_mov_b32_e32 v1, 0x7b
+; GFX9-NEXT:    s_movk_i32 s0, 0x7b
+; GFX9-NEXT:    s_mov_b32 s1, 0
+; GFX9-NEXT:    v_mov_b32_e32 v0, s0
 ; GFX9-NEXT:    v_mov_b32_e32 v2, 0
-; GFX9-NEXT:    ds_write2_b32 v0, v1, v2 offset1:1
-; GFX9-NEXT:    v_mov_b32_e32 v0, 0x7ff8
-; GFX9-NEXT:    ds_write2_b32 v0, v1, v2 offset1:1
+; GFX9-NEXT:    v_mov_b32_e32 v1, s1
+; GFX9-NEXT:    ds_write_b64 v2, v[0:1] offset:16384
+; GFX9-NEXT:    ds_write_b64 v2, v[0:1] offset:32760
 ; GFX9-NEXT:    s_endpgm
   store i64 123, i64 addrspace(3)* getelementptr inbounds ([4096 x i64], [4096 x i64] addrspace(3)* @bar.large, i32 0, i32 2048), align 4
   store i64 123, i64 addrspace(3)* getelementptr inbounds ([4096 x i64], [4096 x i64] addrspace(3)* @bar.large, i32 0, i32 4095), align 4
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment1.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment1.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment1.ll
@@ -0,0 +1,36 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; Properly aligned, same size as alignment.
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [16 x i8], [8 x i8], [4 x i8], [2 x i8], [1 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 16
+
+; CHECK-NOT: @lds.size.1.align.1
+; CHECK-NOT: @lds.size.2.align.2
+; CHECK-NOT: @lds.size.4.align.4
+; CHECK-NOT: @lds.size.8.align.8
+; CHECK-NOT: @lds.size.16.align.16
+@lds.size.1.align.1 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 1
+@lds.size.2.align.2 = internal unnamed_addr addrspace(3) global [2 x i8] undef, align 2
+@lds.size.4.align.4 = internal unnamed_addr addrspace(3) global [4 x i8] undef, align 4
+@lds.size.8.align.8 = internal unnamed_addr addrspace(3) global [8 x i8] undef, align 8
+@lds.size.16.align.16 = internal unnamed_addr addrspace(3) global [16 x i8] undef, align 16
+
+define amdgpu_kernel void @k0() {
+  %lds.size.1.align.1.bc = bitcast [1 x i8] addrspace(3)* @lds.size.1.align.1 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.1.align.1.bc, align 1
+
+  %lds.size.2.align.2.bc = bitcast [2 x i8] addrspace(3)* @lds.size.2.align.2 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.2.align.2.bc, align 2
+
+  %lds.size.4.align.4.bc = bitcast [4 x i8] addrspace(3)* @lds.size.4.align.4 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.4.align.4.bc, align 4
+
+  %lds.size.8.align.8.bc = bitcast [8 x i8] addrspace(3)* @lds.size.8.align.8 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.8.align.8.bc, align 8
+
+  %lds.size.16.align.16.bc = bitcast [16 x i8] addrspace(3)* @lds.size.16.align.16 to i8 addrspace(3)*
+   store i8 5, i8 addrspace(3)* %lds.size.16.align.16.bc, align 16
+
+  ret void
+}
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment2.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment2.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment2.ll
@@ -0,0 +1,37 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; Different properly aligned values, but same size of 1.
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [1 x i8], [7 x i8], [1 x i8], [3 x i8], [1 x i8], [1 x i8], [1 x i8], [1 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 16
+
+; CHECK-NOT: @size.1.align.1
+; CHECK-NOT: @size.1.align.2
+; CHECK-NOT: @size.1.align.4
+; CHECK-NOT: @size.1.align.8
+; CHECK-NOT: @size.1.align.16
+@size.1.align.1 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 1
+@size.1.align.2 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 2
+@size.1.align.4 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 4
+@size.1.align.8 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 8
+@size.1.align.16 = internal unnamed_addr addrspace(3) global [1 x i8] undef, align 16
+
+define amdgpu_kernel void @k0() {
+  %lds.size.1.align.1.bc = bitcast [1 x i8] addrspace(3)* @size.1.align.1 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.1.align.1.bc, align 1
+
+  %lds.size.1.align.2.bc = bitcast [1 x i8] addrspace(3)* @size.1.align.2 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.1.align.2.bc, align 2
+
+  %lds.size.1.align.4.bc = bitcast [1 x i8] addrspace(3)* @size.1.align.4 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.1.align.4.bc, align 4
+
+  %lds.size.1.align.8.bc = bitcast [1 x i8] addrspace(3)* @size.1.align.8 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.1.align.8.bc, align 8
+
+  %lds.size.1.align.16.bc = bitcast [1 x i8] addrspace(3)* @size.1.align.16 to i8 addrspace(3)*
+   store i8 5, i8 addrspace(3)* %lds.size.1.align.16.bc, align 16
+
+  ret void
+}
+
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment3.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment3.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment3.ll
@@ -0,0 +1,32 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; All are under-aligned, requires to fix each on different alignment boundary.
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [9 x i8], [7 x i8], [5 x i8], [3 x i8], [3 x i8], [1 x i8], [2 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 16
+
+; CHECK-NOT: @lds.size.2.align.1
+; CHECK-NOT: @lds.size.3.align.2
+; CHECK-NOT: @lds.size.5.align.4
+; CHECK-NOT: @lds.size.9.align.8
+@lds.size.2.align.1 = internal unnamed_addr addrspace(3) global [2 x i8] undef, align 1
+@lds.size.3.align.2 = internal unnamed_addr addrspace(3) global [3 x i8] undef, align 2
+@lds.size.5.align.4 = internal unnamed_addr addrspace(3) global [5 x i8] undef, align 4
+@lds.size.9.align.8 = internal unnamed_addr addrspace(3) global [9 x i8] undef, align 8
+
+define amdgpu_kernel void @k0() {
+  %lds.size.2.align.1.bc = bitcast [2 x i8] addrspace(3)* @lds.size.2.align.1 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.2.align.1.bc, align 1
+
+  %lds.size.3.align.2.bc = bitcast [3 x i8] addrspace(3)* @lds.size.3.align.2 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.3.align.2.bc, align 2
+
+  %lds.size.5.align.4.bc = bitcast [5 x i8] addrspace(3)* @lds.size.5.align.4 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.5.align.4.bc, align 4
+
+  %lds.size.9.align.8.bc = bitcast [9 x i8] addrspace(3)* @lds.size.9.align.8 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.9.align.8.bc, align 8
+
+  ret void
+}
+
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment4.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment4.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment4.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; All LDS are underaligned, requires to allocate on 16 byte boundary
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [12 x i8], [4 x i8], [11 x i8], [5 x i8], [10 x i8], [6 x i8], [9 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 16
+
+; CHECK-NOT: @lds.size.9.align.1
+; CHECK-NOT: @lds.size.10.align.2
+; CHECK-NOT: @lds.size.11.align.4
+; CHECK-NOT: @lds.size.12.align.8
+@lds.size.9.align.1 = internal unnamed_addr addrspace(3) global [9 x i8] undef, align 1
+@lds.size.10.align.2 = internal unnamed_addr addrspace(3) global [10 x i8] undef, align 2
+@lds.size.11.align.4 = internal unnamed_addr addrspace(3) global [11 x i8] undef, align 4
+@lds.size.12.align.8 = internal unnamed_addr addrspace(3) global [12 x i8] undef, align 8
+
+define amdgpu_kernel void @k0() {
+  %lds.size.9.align.1.bc = bitcast [9 x i8] addrspace(3)* @lds.size.9.align.1 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.9.align.1.bc, align 1
+
+  %lds.size.10.align.2.bc = bitcast [10 x i8] addrspace(3)* @lds.size.10.align.2 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.10.align.2.bc, align 2
+
+  %lds.size.11.align.4.bc = bitcast [11 x i8] addrspace(3)* @lds.size.11.align.4 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.11.align.4.bc, align 4
+
+  %lds.size.12.align.8.bc = bitcast [12 x i8] addrspace(3)* @lds.size.12.align.8 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.12.align.8.bc, align 8
+
+  ret void
+}
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment5.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment5.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment5.ll
@@ -0,0 +1,31 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; All LDS are underaligned, requires to allocate on 8 byte boundary
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [7 x i8], [1 x i8], [7 x i8], [1 x i8], [6 x i8], [2 x i8], [5 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 8
+
+; CHECK-NOT: @lds.size.5.align.2
+; CHECK-NOT: @lds.size.6.align.2
+; CHECK-NOT: @lds.size.7.align.2
+; CHECK-NOT: @lds.size.7.align.4
+@lds.size.5.align.2 = internal unnamed_addr addrspace(3) global [5 x i8] undef, align 2
+@lds.size.6.align.2 = internal unnamed_addr addrspace(3) global [6 x i8] undef, align 2
+@lds.size.7.align.2 = internal unnamed_addr addrspace(3) global [7 x i8] undef, align 2
+@lds.size.7.align.4 = internal unnamed_addr addrspace(3) global [7 x i8] undef, align 4
+
+define amdgpu_kernel void @k0() {
+  %lds.size.5.align.2.bc = bitcast [5 x i8] addrspace(3)* @lds.size.5.align.2 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.5.align.2.bc, align 2
+
+  %lds.size.6.align.2.bc = bitcast [6 x i8] addrspace(3)* @lds.size.6.align.2 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.6.align.2.bc, align 2
+
+  %lds.size.7.align.2.bc = bitcast [7 x i8] addrspace(3)* @lds.size.7.align.2 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.7.align.2.bc, align 2
+
+  %lds.size.7.align.4.bc = bitcast [7 x i8] addrspace(3)* @lds.size.7.align.4 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.7.align.4.bc, align 4
+
+  ret void
+}
diff --git a/llvm/test/CodeGen/AMDGPU/fix-lds-alignment6.ll b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment6.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/fix-lds-alignment6.ll
@@ -0,0 +1,32 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-lower-module-lds < %s | FileCheck %s
+; RUN: opt -S -mtriple=amdgcn-- -passes=amdgpu-lower-module-lds < %s | FileCheck %s
+
+; All LDS are properly aligned on 16 byte boundary, but they are of different size.
+; CHECK: %llvm.amdgcn.kernel.k0.lds.t = type { [20 x i8], [12 x i8], [19 x i8], [13 x i8], [18 x i8], [14 x i8], [17 x i8] }
+; CHECK: @llvm.amdgcn.kernel.k0.lds = internal addrspace(3) global %llvm.amdgcn.kernel.k0.lds.t undef, align 16
+
+; CHECK-NOT: @lds.size.17.align.16
+; CHECK-NOT: @lds.size.18.align.16
+; CHECK-NOT: @lds.size.19.align.16
+; CHECK-NOT: @lds.size.20.align.16
+@lds.size.17.align.16 = internal unnamed_addr addrspace(3) global [17 x i8] undef, align 16
+@lds.size.18.align.16 = internal unnamed_addr addrspace(3) global [18 x i8] undef, align 16
+@lds.size.19.align.16 = internal unnamed_addr addrspace(3) global [19 x i8] undef, align 16
+@lds.size.20.align.16 = internal unnamed_addr addrspace(3) global [20 x i8] undef, align 16
+
+define amdgpu_kernel void @k0() {
+  %lds.size.17.align.16.bc = bitcast [17 x i8] addrspace(3)* @lds.size.17.align.16 to i8 addrspace(3)*
+   store i8 1, i8 addrspace(3)* %lds.size.17.align.16.bc, align 16
+
+  %lds.size.18.align.16.bc = bitcast [18 x i8] addrspace(3)* @lds.size.18.align.16 to i8 addrspace(3)*
+   store i8 2, i8 addrspace(3)* %lds.size.18.align.16.bc, align 16
+
+  %lds.size.19.align.16.bc = bitcast [19 x i8] addrspace(3)* @lds.size.19.align.16 to i8 addrspace(3)*
+   store i8 3, i8 addrspace(3)* %lds.size.19.align.16.bc, align 16
+
+  %lds.size.20.align.16.bc = bitcast [20 x i8] addrspace(3)* @lds.size.20.align.16 to i8 addrspace(3)*
+   store i8 4, i8 addrspace(3)* %lds.size.20.align.16.bc, align 16
+
+  ret void
+}
+
diff --git a/llvm/test/CodeGen/AMDGPU/lds-alignment.ll b/llvm/test/CodeGen/AMDGPU/lds-alignment.ll
--- a/llvm/test/CodeGen/AMDGPU/lds-alignment.ll
+++ b/llvm/test/CodeGen/AMDGPU/lds-alignment.ll
@@ -48,7 +48,7 @@
 
 ; 38 + (2 pad) + 38
 ; HSA-LABEL: {{^}}test_round_size_2_align_8:
-; HSA: workgroup_group_segment_byte_size = 78
+; HSA: workgroup_group_segment_byte_size = 86
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_2_align_8(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align16.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align16.0 to i8 addrspace(3)*
@@ -130,7 +130,7 @@
 ; align 32, 16, 8
 ; 38 + (10 pad) + 38 + (2 pad) + 38 = 126
 ; HSA-LABEL: {{^}}test_round_size_3_order0:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order0(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align32.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align32.0 to i8 addrspace(3)*
@@ -151,7 +151,7 @@
 ; align 32, 8, 16
 ; 38 (+ 10 pad) + 38 + (2 pad) + 38 = 126
 ; HSA-LABEL: {{^}}test_round_size_3_order1:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order1(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align32.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align32.0 to i8 addrspace(3)*
@@ -172,7 +172,7 @@
 ; align 16, 32, 8
 ; 38 + (10 pad) + 38 + (2 pad) + 38 = 126
 ; HSA-LABEL: {{^}}test_round_size_3_order2:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order2(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align16.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align16.0 to i8 addrspace(3)*
@@ -194,7 +194,7 @@
 ; align 16, 8, 32
 ; 38 + (10 pad) + 38 + (2 pad) + 38
 ; HSA-LABEL: {{^}}test_round_size_3_order3:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order3(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align16.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align16.0 to i8 addrspace(3)*
@@ -215,7 +215,7 @@
 ; align 8, 32, 16
 ; 38 + (10 pad) + 38 + (2 pad) + 38 = 126
 ; HSA-LABEL: {{^}}test_round_size_3_order4:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order4(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align8.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align8.0 to i8 addrspace(3)*
@@ -236,7 +236,7 @@
 ; align 8, 16, 32
 ; 38 + (10 pad) + 38 + (2 pad) + 38 = 126
 ; HSA-LABEL: {{^}}test_round_size_3_order5:
-; HSA: workgroup_group_segment_byte_size = 126
+; HSA: workgroup_group_segment_byte_size = 134
 ; HSA: group_segment_alignment = 4
 define amdgpu_kernel void @test_round_size_3_order5(i8 addrspace(1)* %out, i8 addrspace(1)* %in) #1 {
   %lds.align8.0.bc = bitcast [38 x i8] addrspace(3)* @lds.align8.0 to i8 addrspace(3)*
diff --git a/llvm/test/CodeGen/AMDGPU/promote-alloca-globals.ll b/llvm/test/CodeGen/AMDGPU/promote-alloca-globals.ll
--- a/llvm/test/CodeGen/AMDGPU/promote-alloca-globals.ll
+++ b/llvm/test/CodeGen/AMDGPU/promote-alloca-globals.ll
@@ -8,7 +8,7 @@
 ; IR-LABEL: define amdgpu_kernel void @promote_alloca_size_256(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in) {
 ; IR: alloca [10 x i32]
 ; ASM-LABEL: {{^}}promote_alloca_size_256:
-; ASM: .amdgpu_lds llvm.amdgcn.kernel.promote_alloca_size_256.lds, 60000, 4
+; ASM: .amdgpu_lds llvm.amdgcn.kernel.promote_alloca_size_256.lds, 60000, 16
 ; ASM-NOT: .amdgpu_lds
 
 define amdgpu_kernel void @promote_alloca_size_256(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in) {