Index: lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
===================================================================
--- lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
+++ lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
@@ -111,6 +111,8 @@
   case WebAssembly::LOAD8_U_I32:
   case WebAssembly::LOAD8_S_I64:
   case WebAssembly::LOAD8_U_I64:
+  case WebAssembly::ATOMIC_LOAD8_U_I32:
+  case WebAssembly::ATOMIC_LOAD8_U_I64:
   case WebAssembly::STORE8_I32:
   case WebAssembly::STORE8_I64:
     return 0;
@@ -118,6 +120,8 @@
   case WebAssembly::LOAD16_U_I32:
   case WebAssembly::LOAD16_S_I64:
   case WebAssembly::LOAD16_U_I64:
+  case WebAssembly::ATOMIC_LOAD16_U_I32:
+  case WebAssembly::ATOMIC_LOAD16_U_I64:
   case WebAssembly::STORE16_I32:
   case WebAssembly::STORE16_I64:
     return 1;
@@ -129,11 +133,13 @@
   case WebAssembly::LOAD32_U_I64:
   case WebAssembly::STORE32_I64:
   case WebAssembly::ATOMIC_LOAD_I32:
+  case WebAssembly::ATOMIC_LOAD32_U_I64:
     return 2;
   case WebAssembly::LOAD_I64:
   case WebAssembly::LOAD_F64:
   case WebAssembly::STORE_I64:
   case WebAssembly::STORE_F64:
+  case WebAssembly::ATOMIC_LOAD_I64:
     return 3;
   default:
     llvm_unreachable("Only loads and stores have p2align values");
Index: lib/Target/WebAssembly/WebAssemblyInstrAtomics.td
===================================================================
--- lib/Target/WebAssembly/WebAssemblyInstrAtomics.td
+++ lib/Target/WebAssembly/WebAssemblyInstrAtomics.td
@@ -17,19 +17,180 @@
 //===----------------------------------------------------------------------===//
 
 let Defs = [ARGUMENTS] in {
-// TODO: add the rest of the atomic loads
-def ATOMIC_LOAD_I32 : CLoadI32<"i32.atomic.load", 0xfe10>;
-def ATOMIC_LOAD_I64 : CLoadI64<"i64.atomic.load", 0xfe11>;
+def ATOMIC_LOAD_I32 : WebAssemblyLoad<I32, "i32.atomic.load", 0xfe10>;
+def ATOMIC_LOAD_I64 : WebAssemblyLoad<I64, "i64.atomic.load", 0xfe11>;
 } // Defs = [ARGUMENTS]
 
 // Select loads with no constant offset.
 let Predicates = [HasAtomics] in {
-class ALoadPatNoOffset<ValueType ty, SDNode node, I inst> :
-  Pat<(ty (node I32:$addr)), (inst 0, 0, $addr)>;
-def : ALoadPatNoOffset<i32, atomic_load, ATOMIC_LOAD_I32>;
-def : ALoadPatNoOffset<i64, atomic_load, ATOMIC_LOAD_I64>;
+def : LoadPatNoOffset<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatNoOffset<i64, atomic_load_64, ATOMIC_LOAD_I64>;
 
-}
+// Select loads with a constant offset.
+
+// Pattern with address + immediate offset
+def : LoadPatImmOff<i32, atomic_load_32, regPlusImm, ATOMIC_LOAD_I32>;
+def : LoadPatImmOff<i64, atomic_load_64, regPlusImm, ATOMIC_LOAD_I64>;
+def : LoadPatImmOff<i32, atomic_load_32, or_is_add, ATOMIC_LOAD_I32>;
+def : LoadPatImmOff<i64, atomic_load_64, or_is_add, ATOMIC_LOAD_I64>;
+
+def : LoadPatGlobalAddr<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatGlobalAddr<i64, atomic_load_64, ATOMIC_LOAD_I64>;
+
+def : LoadPatExternalSym<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatExternalSym<i64, atomic_load_64, ATOMIC_LOAD_I64>;
+
+
+// Select loads with just a constant offset.
+def : LoadPatOffsetOnly<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatOffsetOnly<i64, atomic_load_64, ATOMIC_LOAD_I64>;
+
+def : LoadPatGlobalAddrOffOnly<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatGlobalAddrOffOnly<i64, atomic_load_64, ATOMIC_LOAD_I64>;
+
+def : LoadPatExternSymOffOnly<i32, atomic_load_32, ATOMIC_LOAD_I32>;
+def : LoadPatExternSymOffOnly<i64, atomic_load_64, ATOMIC_LOAD_I64>;
+
+} // Predicates = [HasAtomics]
+
+// Extending loads. Note that there are only zero-extending atomic loads, no
+// sign-extending loads.
+let Defs = [ARGUMENTS] in {
+def ATOMIC_LOAD8_U_I32 : WebAssemblyLoad<I32, "i32.atomic.load8_u", 0xfe12>;
+def ATOMIC_LOAD16_U_I32 : WebAssemblyLoad<I32, "i32.atomic.load16_u", 0xfe13>;
+def ATOMIC_LOAD8_U_I64 : WebAssemblyLoad<I64, "i64.atomic.load8_u", 0xfe14>;
+def ATOMIC_LOAD16_U_I64 : WebAssemblyLoad<I64, "i64.atomic.load16_u", 0xfe15>;
+def ATOMIC_LOAD32_U_I64 : WebAssemblyLoad<I64, "i64.atomic.load32_u", 0xfe16>;
+} // Defs = [ARGUMENTS]
+
+// Fragments for exending loads. These are different from regular loads because
+// the SDNodes are derived from AtomicSDNode rather than LoadSDNode and
+// therefore don't have the extension type field. So instead of matching that,
+// we match the patterns that the type legalizer expands them to.
+
+// We directly match zext patterns and select the zext atomic loads.
+// i32 (zext (i8 (atomic_load_8))) gets legalized to
+// i32 (and (i32 (atomic_load_8)), 255)
+// These can be selected to a single zero-extending atomic load instruction.
+def zext_aload_8 : PatFrag<(ops node:$addr),
+                           (and (i32 (atomic_load_8 node:$addr)), 255)>;
+def zext_aload_16 : PatFrag<(ops node:$addr),
+                            (and (i32 (atomic_load_16 node:$addr)), 65535)>;
+// Unlike regular loads, extension to i64 is handled differently than i32.
+// i64 (zext (i8 (atomic_load_8))) gets legalized to
+// i64 (and (i64 (anyext (i32 (atomic_load_8)))), 255)
+def zext_aload_8_64 :
+  PatFrag<(ops node:$addr),
+          (and (i64 (anyext (i32 (atomic_load_8 node:$addr)))), 255)>;
+def zext_aload_16_64 :
+  PatFrag<(ops node:$addr),
+          (and (i64 (anyext (i32 (atomic_load_16 node:$addr)))), 65535)>;
+def zext_aload_32_64 :
+  PatFrag<(ops node:$addr),
+          (zext (i32 (atomic_load node:$addr)))>;
+
+// We don't have single sext atomic load instructions. So for sext loads, we
+// match bare subword loads (for 32-bit results) and anyext loads (for 64-bit
+// results) and select a zext load; the next instruction will be sext_inreg
+// which is selected by itself.
+def anyext_aload_8_64 :
+  PatFrag<(ops node:$addr), (anyext (i32 (atomic_load_8 node:$addr)))>;
+def anyext_aload_16_64 :
+  PatFrag<(ops node:$addr), (anyext (i32 (atomic_load_16 node:$addr)))>;
+
+let Predicates = [HasAtomics] in {
+// Select zero-extending loads with no constant offset.
+def : LoadPatNoOffset<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatNoOffset<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatNoOffset<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatNoOffset<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatNoOffset<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+
+// Select sign-extending loads with no constant offset
+def : LoadPatNoOffset<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatNoOffset<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatNoOffset<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatNoOffset<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+// 32->64 sext load gets selected as i32.atomic.load, i64.extend_s/i64
+
+
+// Zero-extending loads with constant offset
+def : LoadPatImmOff<i32, zext_aload_8, regPlusImm, ATOMIC_LOAD8_U_I32>;
+def : LoadPatImmOff<i32, zext_aload_16, regPlusImm, ATOMIC_LOAD16_U_I32>;
+def : LoadPatImmOff<i32, zext_aload_8, or_is_add, ATOMIC_LOAD8_U_I32>;
+def : LoadPatImmOff<i32, zext_aload_16, or_is_add, ATOMIC_LOAD16_U_I32>;
+def : LoadPatImmOff<i64, zext_aload_8_64, regPlusImm, ATOMIC_LOAD8_U_I64>;
+def : LoadPatImmOff<i64, zext_aload_16_64, regPlusImm, ATOMIC_LOAD16_U_I64>;
+def : LoadPatImmOff<i64, zext_aload_32_64, regPlusImm, ATOMIC_LOAD32_U_I64>;
+def : LoadPatImmOff<i64, zext_aload_8_64, or_is_add, ATOMIC_LOAD8_U_I64>;
+def : LoadPatImmOff<i64, zext_aload_16_64, or_is_add, ATOMIC_LOAD16_U_I64>;
+def : LoadPatImmOff<i64, zext_aload_32_64, or_is_add, ATOMIC_LOAD32_U_I64>;
+
+// Sign-extending loads with constant offset
+def : LoadPatImmOff<i32, atomic_load_8, regPlusImm, ATOMIC_LOAD8_U_I32>;
+def : LoadPatImmOff<i32, atomic_load_16, regPlusImm, ATOMIC_LOAD16_U_I32>;
+def : LoadPatImmOff<i32, atomic_load_8, or_is_add, ATOMIC_LOAD8_U_I32>;
+def : LoadPatImmOff<i32, atomic_load_16, or_is_add, ATOMIC_LOAD16_U_I32>;
+def : LoadPatImmOff<i64, anyext_aload_8_64, regPlusImm, ATOMIC_LOAD8_U_I64>;
+def : LoadPatImmOff<i64, anyext_aload_16_64, regPlusImm, ATOMIC_LOAD16_U_I64>;
+def : LoadPatImmOff<i64, anyext_aload_8_64, or_is_add, ATOMIC_LOAD8_U_I64>;
+def : LoadPatImmOff<i64, anyext_aload_16_64, or_is_add, ATOMIC_LOAD16_U_I64>;
+// No 32->64 patterns, just use i32.atomic.load and i64.extend_s/i64
+
+def : LoadPatGlobalAddr<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatGlobalAddr<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatGlobalAddr<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatGlobalAddr<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatGlobalAddr<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+def : LoadPatGlobalAddr<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatGlobalAddr<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatGlobalAddr<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatGlobalAddr<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+
+def : LoadPatExternalSym<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatExternalSym<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatExternalSym<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatExternalSym<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatExternalSym<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+def : LoadPatExternalSym<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatExternalSym<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatExternalSym<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatExternalSym<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+
+
+// Extending loads with just a constant offset
+def : LoadPatOffsetOnly<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatOffsetOnly<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatOffsetOnly<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatOffsetOnly<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatOffsetOnly<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+def : LoadPatOffsetOnly<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatOffsetOnly<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatOffsetOnly<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatOffsetOnly<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+
+def : LoadPatGlobalAddrOffOnly<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatGlobalAddrOffOnly<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatGlobalAddrOffOnly<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatGlobalAddrOffOnly<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatGlobalAddrOffOnly<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+def : LoadPatGlobalAddrOffOnly<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatGlobalAddrOffOnly<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatGlobalAddrOffOnly<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatGlobalAddrOffOnly<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+
+def : LoadPatExternSymOffOnly<i32, zext_aload_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatExternSymOffOnly<i32, zext_aload_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatExternSymOffOnly<i64, zext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatExternSymOffOnly<i64, zext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+def : LoadPatExternSymOffOnly<i64, zext_aload_32_64, ATOMIC_LOAD32_U_I64>;
+def : LoadPatExternSymOffOnly<i32, atomic_load_8, ATOMIC_LOAD8_U_I32>;
+def : LoadPatExternSymOffOnly<i32, atomic_load_16, ATOMIC_LOAD16_U_I32>;
+def : LoadPatExternSymOffOnly<i64, anyext_aload_8_64, ATOMIC_LOAD8_U_I64>;
+def : LoadPatExternSymOffOnly<i64, anyext_aload_16_64, ATOMIC_LOAD16_U_I64>;
+
+
+} // Predicates = [HasAtomics]
 
 //===----------------------------------------------------------------------===//
 // Atomic stores
Index: lib/Target/WebAssembly/WebAssemblyInstrMemory.td
===================================================================
--- lib/Target/WebAssembly/WebAssemblyInstrMemory.td
+++ lib/Target/WebAssembly/WebAssemblyInstrMemory.td
@@ -55,28 +55,19 @@
 
 let Defs = [ARGUMENTS] in {
 
-// Classes to define both atomic and non-atomic integer loads
-class CLoadI32<string Name, int Opcode> :
-  I<(outs I32:$dst),
-    (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-    [], !strconcat(Name, "\t$dst, ${off}(${addr})${p2align}"), Opcode>;
-
-class CLoadI64<string Name, int Opcode> :
-  I<(outs I64:$dst),
+// Defines atomic and non-atomic loads, regular and extending.
+class WebAssemblyLoad<WebAssemblyRegClass rc, string Name, int Opcode> :
+  I<(outs rc:$dst),
     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
     [], !strconcat(Name, "\t$dst, ${off}(${addr})${p2align}"), Opcode>;
 
 // Basic load.
 // FIXME: When we can break syntax compatibility, reorder the fields in the
 // asmstrings to match the binary encoding.
-def LOAD_I32 : CLoadI32<"i32.load", 0x28>;
-def LOAD_I64 : CLoadI64<"i64.load", 0x29>;
-def LOAD_F32 : I<(outs F32:$dst),
-                 (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                 [], "f32.load\t$dst, ${off}(${addr})${p2align}", 0x2a>;
-def LOAD_F64 : I<(outs F64:$dst),
-                 (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                 [], "f64.load\t$dst, ${off}(${addr})${p2align}", 0x2b>;
+def LOAD_I32 : WebAssemblyLoad<I32, "i32.load", 0x28>;
+def LOAD_I64 : WebAssemblyLoad<I64, "i64.load", 0x29>;
+def LOAD_F32 : WebAssemblyLoad<F32, "f32.load", 0x2a>;
+def LOAD_F64 : WebAssemblyLoad<F64, "f64.load", 0x2b>;
 
 } // Defs = [ARGUMENTS]
 
@@ -153,36 +144,16 @@
 let Defs = [ARGUMENTS] in {
 
 // Extending load.
-def LOAD8_S_I32  : I<(outs I32:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i32.load8_s\t$dst, ${off}(${addr})${p2align}", 0x2c>;
-def LOAD8_U_I32  : I<(outs I32:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i32.load8_u\t$dst, ${off}(${addr})${p2align}", 0x2d>;
-def LOAD16_S_I32 : I<(outs I32:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i32.load16_s\t$dst, ${off}(${addr})${p2align}", 0x2e>;
-def LOAD16_U_I32 : I<(outs I32:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i32.load16_u\t$dst, ${off}(${addr})${p2align}", 0x2f>;
-def LOAD8_S_I64  : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load8_s\t$dst, ${off}(${addr})${p2align}", 0x30>;
-def LOAD8_U_I64  : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load8_u\t$dst, ${off}(${addr})${p2align}", 0x31>;
-def LOAD16_S_I64 : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load16_s\t$dst, ${off}(${addr})${p2align}", 0x32>;
-def LOAD16_U_I64 : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load16_u\t$dst, ${off}(${addr})${p2align}", 0x33>;
-def LOAD32_S_I64 : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load32_s\t$dst, ${off}(${addr})${p2align}", 0x34>;
-def LOAD32_U_I64 : I<(outs I64:$dst),
-                     (ins P2Align:$p2align, offset32_op:$off, I32:$addr),
-                     [], "i64.load32_u\t$dst, ${off}(${addr})${p2align}", 0x35>;
+def LOAD8_S_I32 : WebAssemblyLoad<I32, "i32.load8_s", 0x2c>;
+def LOAD8_U_I32 : WebAssemblyLoad<I32, "i32.load8_u", 0x2d>;
+def LOAD16_S_I32 : WebAssemblyLoad<I32, "i32.load16_s", 0x2e>;
+def LOAD16_U_I32 : WebAssemblyLoad<I32, "i32.load16_u", 0x2f>;
+def LOAD8_S_I64 : WebAssemblyLoad<I64, "i64.load8_s", 0x30>;
+def LOAD8_U_I64 : WebAssemblyLoad<I64, "i64.load8_u", 0x31>;
+def LOAD16_S_I64 : WebAssemblyLoad<I64, "i64.load16_s", 0x32>;
+def LOAD16_U_I64 : WebAssemblyLoad<I64, "i64.load16_u", 0x32>;
+def LOAD32_S_I64 : WebAssemblyLoad<I64, "i64.load32_s", 0x34>;
+def LOAD32_U_I64 : WebAssemblyLoad<I64, "i64.load32_u", 0x35>;
 
 } // Defs = [ARGUMENTS]
 
@@ -290,7 +261,6 @@
 def : LoadPatNoOffset<i64, extloadi16, LOAD16_U_I64>;
 def : LoadPatNoOffset<i64, extloadi32, LOAD32_U_I64>;
 
-
 // Select "don't care" extending loads with a constant offset.
 def : LoadPatImmOff<i32, extloadi8, regPlusImm, LOAD8_U_I32>;
 def : LoadPatImmOff<i32, extloadi16, regPlusImm, LOAD16_U_I32>;
@@ -313,7 +283,6 @@
 def : LoadPatExternalSym<i64, extloadi16, LOAD16_U_I64>;
 def : LoadPatExternalSym<i64, extloadi32, LOAD32_U_I64>;
 
-
 // Select "don't care" extending loads with just a constant offset.
 def : LoadPatOffsetOnly<i32, extloadi8, LOAD8_U_I32>;
 def : LoadPatOffsetOnly<i32, extloadi16, LOAD16_U_I32>;
Index: lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
===================================================================
--- lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
+++ lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
@@ -97,6 +97,12 @@
       case WebAssembly::LOAD32_S_I64:
       case WebAssembly::LOAD32_U_I64:
       case WebAssembly::ATOMIC_LOAD_I32:
+      case WebAssembly::ATOMIC_LOAD8_U_I32:
+      case WebAssembly::ATOMIC_LOAD16_U_I32:
+      case WebAssembly::ATOMIC_LOAD_I64:
+      case WebAssembly::ATOMIC_LOAD8_U_I64:
+      case WebAssembly::ATOMIC_LOAD16_U_I64:
+      case WebAssembly::ATOMIC_LOAD32_U_I64:
         RewriteP2Align(MI, WebAssembly::LoadP2AlignOperandNo);
         break;
       case WebAssembly::STORE_I32:
Index: test/CodeGen/WebAssembly/atomics.ll
===================================================================
--- test/CodeGen/WebAssembly/atomics.ll
+++ /dev/null
@@ -1,16 +0,0 @@
-; RUN: not llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt 
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals -mattr=+atomics | FileCheck %s
-
-; Test that atomic loads are assembled properly.
-
-target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
-target triple = "wasm32-unknown-unknown-wasm"
-
-; CHECK-LABEL: load_i32_atomic:
-; CHECK: i32.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
-; CHECK-NEXT: return $pop[[NUM]]{{$}}
-
-define i32 @load_i32_atomic(i32 *%p) {
-  %v = load atomic i32, i32* %p seq_cst, align 4
-  ret i32 %v
-}
Index: test/CodeGen/WebAssembly/i32-load-store-alignment.ll
===================================================================
--- test/CodeGen/WebAssembly/i32-load-store-alignment.ll
+++ test/CodeGen/WebAssembly/i32-load-store-alignment.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
+; RUN: llc < %s -mattr=+atomics -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
 
 ; Test loads and stores with custom alignment values.
 
@@ -210,3 +210,29 @@
   store i16 %v, i16* %p, align 4
   ret void
 }
+
+; Atomics.
+; Wasm atomics have the alignment field, but it must always have the
+; type's natural alignment.
+
+; CHECK-LABEL: ldi32_atomic_a4:
+; CHECK-NEXT: .param i32{{$}}
+; CHECK-NEXT: .result i32{{$}}
+; CHECK-NEXT: i32.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i32 @ldi32_atomic_a4(i32 *%p) {
+  %v = load atomic i32, i32* %p seq_cst, align 4
+  ret i32 %v
+}
+
+; 8 is greater than the default alignment so it is rounded down to 4
+
+; CHECK-LABEL: ldi32_atomic_a8:
+; CHECK-NEXT: .param i32{{$}}
+; CHECK-NEXT: .result i32{{$}}
+; CHECK-NEXT: i32.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i32 @ldi32_atomic_a8(i32 *%p) {
+  %v = load atomic i32, i32* %p seq_cst, align 8
+  ret i32 %v
+}
Index: test/CodeGen/WebAssembly/i64-load-store-alignment.ll
===================================================================
--- test/CodeGen/WebAssembly/i64-load-store-alignment.ll
+++ test/CodeGen/WebAssembly/i64-load-store-alignment.ll
@@ -1,4 +1,4 @@
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
+; RUN: llc < %s -mattr=+atomics -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
 
 ; Test loads and stores with custom alignment values.
 
@@ -323,3 +323,26 @@
   store i32 %v, i32* %p, align 8
   ret void
 }
+
+; Atomics.
+; CHECK-LABEL: ldi64_atomic_a8:
+; CHECK-NEXT: .param i32{{$}}
+; CHECK-NEXT: .result i64{{$}}
+; CHECK-NEXT: i64.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i64 @ldi64_atomic_a8(i64 *%p) {
+  %v = load atomic i64, i64* %p seq_cst, align 8
+  ret i64 %v
+}
+
+; 16 is greater than the default alignment so it is ignored.
+
+; CHECK-LABEL: ldi64_atomic_a16:
+; CHECK-NEXT: .param i32{{$}}
+; CHECK-NEXT: .result i64{{$}}
+; CHECK-NEXT: i64.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i64 @ldi64_atomic_a16(i64 *%p) {
+  %v = load atomic i64, i64* %p seq_cst, align 16
+  ret i64 %v
+}
Index: test/CodeGen/WebAssembly/load-ext-atomic.ll
===================================================================
--- /dev/null
+++ test/CodeGen/WebAssembly/load-ext-atomic.ll
@@ -0,0 +1,102 @@
+; RUN: llc < %s -mattr=+atomics -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
+
+; Test that extending loads are assembled properly.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+; CHECK-LABEL: sext_i8_i32:
+; CHECK: i32.atomic.load8_u $push0=, 0($0){{$}}
+; CHECK-NEXT: i32.extend8_s $push1=, $pop0{{$}}
+; CHECK-NEXT: return $pop1{{$}}
+define i32 @sext_i8_i32(i8 *%p) {
+  %v = load atomic i8, i8* %p seq_cst, align 1
+  %e = sext i8 %v to i32
+  ret i32 %e
+}
+
+; CHECK-LABEL: zext_i8_i32:
+; CHECK: i32.atomic.load8_u $push0=, 0($0){{$}}
+; CHECK-NEXT: return $pop0{{$}}
+define i32 @zext_i8_i32(i8 *%p) {
+e1:
+  %v = load atomic i8, i8* %p seq_cst, align 1
+  %e = zext i8 %v to i32
+  ret i32 %e
+}
+
+; CHECK-LABEL: sext_i16_i32:
+; CHECK: i32.atomic.load16_u $push0=, 0($0){{$}}
+; CHECK-NEXT: i32.extend16_s $push1=, $pop0{{$}}
+; CHECK-NEXT: return $pop1{{$}}
+define i32 @sext_i16_i32(i16 *%p) {
+  %v = load atomic i16, i16* %p seq_cst, align 2
+  %e = sext i16 %v to i32
+  ret i32 %e
+}
+
+; CHECK-LABEL: zext_i16_i32:
+; CHECK: i32.atomic.load16_u $push0=, 0($0){{$}}
+; CHECK-NEXT: return $pop0{{$}}
+define i32 @zext_i16_i32(i16 *%p) {
+  %v = load atomic i16, i16* %p seq_cst, align 2
+  %e = zext i16 %v to i32
+  ret i32 %e
+}
+
+; CHECK-LABEL: sext_i8_i64:
+; CHECK: i64.atomic.load8_u $push0=, 0($0){{$}}
+; CHECK: i64.extend8_s $push1=, $pop0{{$}}
+; CHECK-NEXT: return $pop1{{$}}
+define i64 @sext_i8_i64(i8 *%p) {
+  %v = load atomic i8, i8* %p seq_cst, align 1
+  %e = sext i8 %v to i64
+  ret i64 %e
+}
+
+; CHECK-LABEL: zext_i8_i64:
+; CHECK: i64.atomic.load8_u $push0=, 0($0){{$}}
+; CHECK-NEXT: return $pop0{{$}}
+define i64 @zext_i8_i64(i8 *%p) {
+  %v = load atomic i8, i8* %p seq_cst, align 1
+  %e = zext i8 %v to i64
+  ret i64 %e
+}
+
+; CHECK-LABEL: sext_i16_i64:
+; CHECK: i64.atomic.load16_u $push0=, 0($0){{$}}
+; CHECK: i64.extend16_s $push1=, $pop0{{$}}
+; CHECK-NEXT: return $pop1{{$}}
+define i64 @sext_i16_i64(i16 *%p) {
+  %v = load atomic i16, i16* %p seq_cst, align 2
+  %e = sext i16 %v to i64
+  ret i64 %e
+}
+
+; CHECK-LABEL: zext_i16_i64:
+; CHECK: i64.atomic.load16_u $push0=, 0($0){{$}}
+; CHECK-NEXT: return $pop0{{$}}
+define i64 @zext_i16_i64(i16 *%p) {
+  %v = load atomic i16, i16* %p seq_cst, align 2
+  %e = zext i16 %v to i64
+  ret i64 %e
+}
+
+; CHECK-LABEL: sext_i32_i64:
+; CHECK: i32.atomic.load $push0=, 0($0){{$}}
+; CHECK: i64.extend_s/i32 $push1=, $pop0{{$}}
+; CHECK-NEXT: return $pop1{{$}}
+define i64 @sext_i32_i64(i32 *%p) {
+  %v = load atomic i32, i32* %p seq_cst, align 4
+  %e = sext i32 %v to i64
+  ret i64 %e
+}
+
+; CHECK-LABEL: zext_i32_i64:
+; CHECK: i64.atomic.load32_u $push0=, 0($0){{$}}
+; CHECK: return $pop0{{$}}
+define i64 @zext_i32_i64(i32 *%p) {
+  %v = load atomic i32, i32* %p seq_cst, align 4
+  %e = zext i32 %v to i64
+  ret i64 %e
+}
Index: test/CodeGen/WebAssembly/offset-atomics.ll
===================================================================
--- /dev/null
+++ test/CodeGen/WebAssembly/offset-atomics.ll
@@ -0,0 +1,307 @@
+; RUN: not llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals -mattr=+atomics | FileCheck %s
+
+; Test that atomic loads are assembled properly.
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+; CHECK-LABEL: load_i32_no_offset:
+; CHECK: i32.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i32 @load_i32_no_offset(i32 *%p) {
+  %v = load atomic i32, i32* %p seq_cst, align 4
+  ret i32 %v
+}
+
+; With an nuw add, we can fold an offset.
+
+; CHECK-LABEL: load_i32_with_folded_offset:
+; CHECK: i32.atomic.load  $push0=, 24($0){{$}}
+define i32 @load_i32_with_folded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+; With an inbounds gep, we can fold an offset.
+
+; CHECK-LABEL: load_i32_with_folded_gep_offset:
+; CHECK: i32.atomic.load  $push0=, 24($0){{$}}
+define i32 @load_i32_with_folded_gep_offset(i32* %p) {
+  %s = getelementptr inbounds i32, i32* %p, i32 6
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+; We can't fold a negative offset though, even with an inbounds gep.
+
+; CHECK-LABEL: load_i32_with_unfolded_gep_negative_offset:
+; CHECK: i32.const $push0=, -24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i32.atomic.load  $push2=, 0($pop1){{$}}
+define i32 @load_i32_with_unfolded_gep_negative_offset(i32* %p) {
+  %s = getelementptr inbounds i32, i32* %p, i32 -6
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+; Without nuw, and even with nsw, we can't fold an offset.
+
+; CHECK-LABEL: load_i32_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i32.atomic.load  $push2=, 0($pop1){{$}}
+define i32 @load_i32_with_unfolded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+; Without inbounds, we can't fold a gep offset.
+
+; CHECK-LABEL: load_i32_with_unfolded_gep_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i32.atomic.load  $push2=, 0($pop1){{$}}
+define i32 @load_i32_with_unfolded_gep_offset(i32* %p) {
+  %s = getelementptr i32, i32* %p, i32 6
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+; CHECK-LABEL: load_i64_no_offset:
+; CHECK: i64.atomic.load $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i64 @load_i64_no_offset(i64 *%p) {
+  %v = load atomic i64, i64* %p seq_cst, align 8
+  ret i64 %v
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_folded_offset:
+; CHECK: i64.atomic.load  $push0=, 24($0){{$}}
+define i64 @load_i64_with_folded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  %t = load atomic i64, i64* %s seq_cst, align 8
+  ret i64 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_folded_gep_offset:
+; CHECK: i64.atomic.load  $push0=, 24($0){{$}}
+define i64 @load_i64_with_folded_gep_offset(i64* %p) {
+  %s = getelementptr inbounds i64, i64* %p, i32 3
+  %t = load atomic i64, i64* %s seq_cst, align 8
+  ret i64 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_unfolded_gep_negative_offset:
+; CHECK: i32.const $push0=, -24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i64.atomic.load  $push2=, 0($pop1){{$}}
+define i64 @load_i64_with_unfolded_gep_negative_offset(i64* %p) {
+  %s = getelementptr inbounds i64, i64* %p, i32 -3
+  %t = load atomic i64, i64* %s seq_cst, align 8
+  ret i64 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_unfolded_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i64.atomic.load  $push2=, 0($pop1){{$}}
+define i64 @load_i64_with_unfolded_offset(i64* %p) {
+  %q = ptrtoint i64* %p to i32
+  %r = add nsw i32 %q, 24
+  %s = inttoptr i32 %r to i64*
+  %t = load atomic i64, i64* %s seq_cst, align 8
+  ret i64 %t
+}
+
+; Same as above but with i64.
+
+; CHECK-LABEL: load_i64_with_unfolded_gep_offset:
+; CHECK: i32.const $push0=, 24{{$}}
+; CHECK: i32.add   $push1=, $0, $pop0{{$}}
+; CHECK: i64.atomic.load  $push2=, 0($pop1){{$}}
+define i64 @load_i64_with_unfolded_gep_offset(i64* %p) {
+  %s = getelementptr i64, i64* %p, i32 3
+  %t = load atomic i64, i64* %s seq_cst, align 8
+  ret i64 %t
+}
+
+; CHECK-LABEL: load_i32_with_folded_or_offset:
+; CHECK: i32.atomic.load8_u $push[[R1:[0-9]+]]=, 2($pop{{[0-9]+}}){{$}}
+; CHECK-NEXT: i32.extend8_s $push{{[0-9]+}}=, $pop[[R1]]{{$}}
+define i32 @load_i32_with_folded_or_offset(i32 %x) {
+  %and = and i32 %x, -4
+  %t0 = inttoptr i32 %and to i8*
+  %arrayidx = getelementptr inbounds i8, i8* %t0, i32 2
+  %t1 = load atomic i8, i8* %arrayidx seq_cst, align 8
+  %conv = sext i8 %t1 to i32
+  ret i32 %conv
+}
+
+; When loading from a fixed address, materialize a zero.
+
+; CHECK-LABEL: load_i32_from_numeric_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.atomic.load  $push1=, 42($pop0){{$}}
+define i32 @load_i32_from_numeric_address() {
+  %s = inttoptr i32 42 to i32*
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  ret i32 %t
+}
+
+
+; CHECK-LABEL: load_i32_from_global_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.atomic.load  $push1=, gv($pop0){{$}}
+@gv = global i32 0
+define i32 @load_i32_from_global_address() {
+  %t = load atomic i32, i32* @gv seq_cst, align 4
+  ret i32 %t
+}
+
+; Fold an offset into a sign-extending load.
+
+; CHECK-LABEL: load_i8_s_with_folded_offset:
+; CHECK: i32.atomic.load8_u $push0=, 24($0){{$}}
+; CHECK-NEXT: i32.extend8_s $push1=, $pop0
+define i32 @load_i8_s_with_folded_offset(i8* %p) {
+  %q = ptrtoint i8* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i8*
+  %t = load atomic i8, i8* %s seq_cst, align 1
+  %u = sext i8 %t to i32
+  ret i32 %u
+}
+
+; Fold a gep offset into a sign-extending load.
+
+; CHECK-LABEL: load_i8_s_with_folded_gep_offset:
+; CHECK: i32.atomic.load8_u $push0=, 24($0){{$}}
+; CHECK-NEXT: i32.extend8_s $push1=, $pop0
+define i32 @load_i8_s_with_folded_gep_offset(i8* %p) {
+  %s = getelementptr inbounds i8, i8* %p, i32 24
+  %t = load atomic i8, i8* %s seq_cst, align 1
+  %u = sext i8 %t to i32
+  ret i32 %u
+}
+
+; CHECK-LABEL: load_i16_s_i64_with_folded_gep_offset:
+; CHECK: i64.atomic.load16_u  $push0=, 6($0){{$}}
+define i64 @load_i16_s_i64_with_folded_gep_offset(i16* %p) {
+  %s = getelementptr inbounds i16, i16* %p, i32 3
+  %t = load atomic i16, i16* %s seq_cst, align 2
+  %u = zext i16 %t to i64
+  ret i64 %u
+}
+
+; CHECK-LABEL: load_i64_with_folded_or_offset:
+; CHECK: i64.atomic.load8_u $push[[R1:[0-9]+]]=, 2($pop{{[0-9]+}}){{$}}
+; CHECK-NEXT: i64.extend8_s $push{{[0-9]+}}=, $pop[[R1]]{{$}}
+define i64 @load_i64_with_folded_or_offset(i32 %x) {
+  %and = and i32 %x, -4
+  %t0 = inttoptr i32 %and to i8*
+  %arrayidx = getelementptr inbounds i8, i8* %t0, i32 2
+  %t1 = load atomic i8, i8* %arrayidx seq_cst, align 8
+  %conv = sext i8 %t1 to i64
+  ret i64 %conv
+}
+
+
+; Fold an offset into a zero-extending load.
+
+; CHECK-LABEL: load_i16_u_with_folded_offset:
+; CHECK: i32.atomic.load16_u $push0=, 24($0){{$}}
+define i32 @load_i16_u_with_folded_offset(i8* %p) {
+  %q = ptrtoint i8* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i16*
+  %t = load atomic i16, i16* %s seq_cst, align 2
+  %u = zext i16 %t to i32
+  ret i32 %u
+}
+
+; Fold a gep offset into a zero-extending load.
+
+; CHECK-LABEL: load_i8_u_with_folded_gep_offset:
+; CHECK: i32.atomic.load8_u $push0=, 24($0){{$}}
+define i32 @load_i8_u_with_folded_gep_offset(i8* %p) {
+  %s = getelementptr inbounds i8, i8* %p, i32 24
+  %t = load atomic i8, i8* %s seq_cst, align 1
+  %u = zext i8 %t to i32
+  ret i32 %u
+}
+
+
+; When loading from a fixed address, materialize a zero.
+; As above but with extending load.
+
+; CHECK-LABEL: load_zext_i32_from_numeric_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.atomic.load16_u  $push1=, 42($pop0){{$}}
+define i32 @load_zext_i32_from_numeric_address() {
+  %s = inttoptr i32 42 to i16*
+  %t = load atomic i16, i16* %s seq_cst, align 2
+  %u = zext i16 %t to i32
+  ret i32 %u
+}
+
+; CHECK-LABEL: load_sext_i32_from_global_address
+; CHECK: i32.const $push0=, 0{{$}}
+; CHECK: i32.atomic.load8_u  $push1=, gv8($pop0){{$}}
+; CHECK-NEXT: i32.extend8_s $push2=, $pop1{{$}}
+@gv8 = global i8 0
+define i32 @load_sext_i32_from_global_address() {
+  %t = load atomic i8, i8* @gv8 seq_cst, align 1
+  %u = sext i8 %t to i32
+  ret i32 %u
+}
+
+; Fold an offset into a sign-extending load.
+; As above but 32 extended to 64 bit.
+; CHECK-LABEL: load_i32_i64_s_with_folded_offset:
+; CHECK: i32.atomic.load $push0=, 24($0){{$}}
+; CHECK-NEXT: i64.extend_s/i32 $push1=, $pop0{{$}}
+define i64 @load_i32_i64_s_with_folded_offset(i32* %p) {
+  %q = ptrtoint i32* %p to i32
+  %r = add nuw i32 %q, 24
+  %s = inttoptr i32 %r to i32*
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  %u = sext i32 %t to i64
+  ret i64 %u
+}
+
+; Fold a gep offset into a zero-extending load.
+; As above but 32 extended to 64 bit.
+; CHECK-LABEL: load_i32_i64_u_with_folded_gep_offset:
+; CHECK: i64.atomic.load32_u $push0=, 96($0){{$}}
+define i64 @load_i32_i64_u_with_folded_gep_offset(i32* %p) {
+  %s = getelementptr inbounds i32, i32* %p, i32 24
+  %t = load atomic i32, i32* %s seq_cst, align 4
+  %u = zext i32 %t to i64
+  ret i64 %u
+}
+
+; i8 return value should test anyext loads
+; CHECK-LABEL: ldi8_a1:
+; CHECK-NEXT: i32.atomic.load8_u $push[[NUM:[0-9]+]]=, 0($0){{$}}
+; CHECK-NEXT: return $pop[[NUM]]{{$}}
+define i8 @ldi8_a1(i8 *%p) {
+  %v = load atomic i8, i8* %p seq_cst, align 1
+  ret i8 %v
+}