Index: lib/Target/AMDGPU/AMDGPU.td
===================================================================
--- lib/Target/AMDGPU/AMDGPU.td
+++ lib/Target/AMDGPU/AMDGPU.td
@@ -67,6 +67,12 @@
   "Support unaligned global loads and stores"
 >;
 
+def FeatureUnalignedScratchAccess : SubtargetFeature<"unaligned-scratch-access",
+  "UnalignedScratchAccess",
+  "true",
+  "Support unaligned scratch loads and stores"
+>;
+
 def FeatureXNACK : SubtargetFeature<"xnack",
   "EnableXNACK",
   "true",
Index: lib/Target/AMDGPU/AMDGPUSubtarget.h
===================================================================
--- lib/Target/AMDGPU/AMDGPUSubtarget.h
+++ lib/Target/AMDGPU/AMDGPUSubtarget.h
@@ -76,6 +76,7 @@
   bool FP64Denormals;
   bool FPExceptions;
   bool FlatForGlobal;
+  bool UnalignedScratchAccess;
   bool UnalignedBufferAccess;
   bool EnableXNACK;
   bool DebuggerInsertNops;
@@ -275,6 +276,10 @@
     return UnalignedBufferAccess;
   }
 
+  bool hasUnalignedScratchAccess() const {
+    return UnalignedScratchAccess;
+  }
+
   bool isXNACKEnabled() const {
     return EnableXNACK;
   }
Index: lib/Target/AMDGPU/AMDGPUSubtarget.cpp
===================================================================
--- lib/Target/AMDGPU/AMDGPUSubtarget.cpp
+++ lib/Target/AMDGPU/AMDGPUSubtarget.cpp
@@ -85,6 +85,7 @@
     FP64Denormals(false),
     FPExceptions(false),
     FlatForGlobal(false),
+    UnalignedScratchAccess(false),
     UnalignedBufferAccess(false),
 
     EnableXNACK(false),
Index: lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- lib/Target/AMDGPU/SIISelLowering.cpp
+++ lib/Target/AMDGPU/SIISelLowering.cpp
@@ -453,6 +453,15 @@
     return AlignedBy4;
   }
 
+  // FIXME: We have to be conservative here and assume that flat operations
+  // will access scratch.  If we had access to the IR function, then we
+  // could determine if any private memory was used in the function.
+  if (!Subtarget->hasUnalignedScratchAccess() &&
+      (AddrSpace == AMDGPUAS::PRIVATE_ADDRESS ||
+       AddrSpace == AMDGPUAS::FLAT_ADDRESS)) {
+    return false;
+  }
+
   if (Subtarget->hasUnalignedBufferAccess()) {
     // If we have an uniform constant load, it still requires using a slow
     // buffer instruction if unaligned.
Index: test/CodeGen/AMDGPU/flat-address-space.ll
===================================================================
--- test/CodeGen/AMDGPU/flat-address-space.ll
+++ test/CodeGen/AMDGPU/flat-address-space.ll
@@ -1,7 +1,7 @@
-; RUN: llc -O0 -march=amdgcn -mcpu=bonaire -mattr=-promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-NO-PROMOTE %s
-; RUN: llc -O0 -march=amdgcn -mcpu=bonaire -mattr=+promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-PROMOTE %s
-; RUN: llc -O0 -march=amdgcn -mcpu=tonga -mattr=-promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-NO-PROMOTE %s
-; RUN: llc -O0 -march=amdgcn -mcpu=tonga -mattr=+promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-PROMOTE %s
+; RUN: llc -O0 -mtriple=amdgcn-mesa-mesa3d -mcpu=bonaire -mattr=-promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-NO-PROMOTE %s
+; RUN: llc -O0 -mtriple=amdgcn-mesa-mesa3d -mcpu=bonaire -mattr=+promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-PROMOTE %s
+; RUN: llc -O0 -mtriple=amdgcn-mesa-mesa3d -mcpu=tonga -mattr=-promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-NO-PROMOTE %s
+; RUN: llc -O0 -mtriple=amdgcn-mesa-mesa3d -mcpu=tonga -mattr=+promote-alloca < %s | FileCheck -check-prefix=CHECK -check-prefix=CHECK-PROMOTE %s
 
 ; Disable optimizations in case there are optimizations added that
 ; specialize away generic pointer accesses.
@@ -73,7 +73,7 @@
 ; CHECK: flat_load_dwordx2
 define void @load_flat_i64(i64 addrspace(1)* noalias %out, i64 addrspace(1)* noalias %gptr) #0 {
   %fptr = addrspacecast i64 addrspace(1)* %gptr to i64 addrspace(4)*
-  %fload = load i64, i64 addrspace(4)* %fptr, align 4
+  %fload = load i64, i64 addrspace(4)* %fptr, align 8
   store i64 %fload, i64 addrspace(1)* %out, align 8
   ret void
 }
@@ -82,7 +82,7 @@
 ; CHECK: flat_load_dwordx4
 define void @load_flat_v4i32(<4 x i32> addrspace(1)* noalias %out, <4 x i32> addrspace(1)* noalias %gptr) #0 {
   %fptr = addrspacecast <4 x i32> addrspace(1)* %gptr to <4 x i32> addrspace(4)*
-  %fload = load <4 x i32>, <4 x i32> addrspace(4)* %fptr, align 4
+  %fload = load <4 x i32>, <4 x i32> addrspace(4)* %fptr, align 32
   store <4 x i32> %fload, <4 x i32> addrspace(1)* %out, align 8
   ret void
 }
@@ -127,6 +127,30 @@
   ret void
 }
 
+; CHECK-LABEL: flat_scratch_unaligned_load:
+; CHECK: flat_load_ubyte
+; CHECK: flat_load_ubyte
+; CHECK: flat_load_ubyte
+; CHECK: flat_load_ubyte
+define void @flat_scratch_unaligned_load() {
+  %scratch = alloca i32
+  %fptr = addrspacecast i32* %scratch to i32 addrspace(4)*
+  %ld = load volatile i32, i32 addrspace(4)* %fptr, align 1
+  ret void
+}
+
+; CHECK-LABEL: flat_scratch_unaligned_store:
+; CHECK: flat_store_byte
+; CHECK: flat_store_byte
+; CHECK: flat_store_byte
+; CHECK: flat_store_byte
+define void @flat_scratch_unaligned_store() {
+  %scratch = alloca i32
+  %fptr = addrspacecast i32* %scratch to i32 addrspace(4)*
+  store volatile i32 0, i32 addrspace(4)* %fptr, align 1
+  ret void
+}
+
 attributes #0 = { nounwind }
 attributes #1 = { nounwind convergent }
 attributes #3 = { nounwind readnone }
Index: test/CodeGen/AMDGPU/scratch-buffer.ll
===================================================================
--- test/CodeGen/AMDGPU/scratch-buffer.ll
+++ test/CodeGen/AMDGPU/scratch-buffer.ll
@@ -108,3 +108,25 @@
   store i32 %val, i32 addrspace(1)* %out
   ret void
 }
+
+; GCN-LABEL: scratch_unaligned_load:
+; GCN: buffer_load_ubyte
+; GCN: buffer_load_ubyte
+; GCN: buffer_load_ubyte
+; GCN: buffer_load_ubyte
+define void @scratch_unaligned_load() {
+  %scratch = alloca i32
+  %ld = load volatile i32, i32* %scratch, align 1
+  ret void
+}
+
+; GCN-LABEL: scratch_unaligned_store:
+; GCN: buffer_store_byte
+; GCN: buffer_store_byte
+; GCN: buffer_store_byte
+; GCN: buffer_store_byte
+define void @scratch_unaligned_store() {
+  %scratch = alloca i32
+  store volatile i32 0, i32 * %scratch, align 1
+  ret void
+}