Index: include/llvm/IR/IntrinsicsAArch64.td
===================================================================
--- include/llvm/IR/IntrinsicsAArch64.td
+++ include/llvm/IR/IntrinsicsAArch64.td
@@ -33,6 +33,11 @@
                                 LLVMMatchType<0>], [IntrNoMem]>;
 
 //===----------------------------------------------------------------------===//
+// HINT
+
+def int_aarch64_hint : Intrinsic<[], [llvm_i32_ty]>;
+
+//===----------------------------------------------------------------------===//
 // RBIT
 
 def int_aarch64_rbit : Intrinsic<[llvm_anyint_ty], [LLVMMatchType<0>],
Index: lib/Target/AArch64/AArch64InstrFormats.td
===================================================================
--- lib/Target/AArch64/AArch64InstrFormats.td
+++ lib/Target/AArch64/AArch64InstrFormats.td
@@ -764,15 +764,17 @@
 
 // Base encoding for system instruction operands.
 let mayLoad = 0, mayStore = 0, hasSideEffects = 1 in
-class BaseSystemI<bit L, dag oops, dag iops, string asm, string operands>
-    : I<oops, iops, asm, operands, "", []> {
+class BaseSystemI<bit L, dag oops, dag iops, string asm, string operands,
+                  list<dag> pattern = []>
+    : I<oops, iops, asm, operands, "", pattern> {
   let Inst{31-22} = 0b1101010100;
   let Inst{21}    = L;
 }
 
 // System instructions which do not have an Rt register.
-class SimpleSystemI<bit L, dag iops, string asm, string operands>
-    : BaseSystemI<L, (outs), iops, asm, operands> {
+class SimpleSystemI<bit L, dag iops, string asm, string operands,
+                    list<dag> pattern = []>
+    : BaseSystemI<L, (outs), iops, asm, operands, pattern> {
   let Inst{4-0} = 0b11111;
 }
 
@@ -785,13 +787,17 @@
 }
 
 // Hint instructions that take both a CRm and a 3-bit immediate.
-class HintI<string mnemonic>
-    : SimpleSystemI<0, (ins imm0_127:$imm), mnemonic#" $imm", "">,
-      Sched<[WriteHint]> {
-  bits <7> imm;
-  let Inst{20-12} = 0b000110010;
-  let Inst{11-5} = imm;
-}
+// NOTE: ideally, this would have mayStore = 0, mayLoad = 0, but we cannot
+// model patterns with sufficiently fine granularity
+let mayStore = 1, mayLoad = 1, hasSideEffects = 1 in
+  class HintI<string mnemonic>
+      : SimpleSystemI<0, (ins imm0_127:$imm), mnemonic#" $imm", "",
+                      [(int_aarch64_hint imm0_127:$imm)]>,
+        Sched<[WriteHint]> {
+    bits <7> imm;
+    let Inst{20-12} = 0b000110010;
+    let Inst{11-5} = imm;
+  }
 
 // System instructions taking a single literal operand which encodes into
 // CRm. op2 differentiates the opcodes.
Index: test/CodeGen/AArch64/hints.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AArch64/hints.ll
@@ -0,0 +1,67 @@
+; RUN: llc -mtriple aarch64-eabi -o - %s | FileCheck %s
+
+declare void @llvm.aarch64.hint(i32) nounwind
+
+define void @hint_nop() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 0) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_nop
+; CHECK: nop
+
+define void @hint_yield() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 1) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_yield
+; CHECK: yield
+
+define void @hint_wfe() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 2) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_wfe
+; CHECK: wfe
+
+define void @hint_wfi() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 3) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_wfi
+; CHECK: wfi
+
+define void @hint_sev() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 4) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_sev
+; CHECK: sev
+
+define void @hint_sevl() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 5) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_sevl
+; CHECK: sevl
+
+define void @hint_undefined() {
+entry:
+  tail call void @llvm.aarch64.hint(i32 8) nounwind
+  ret void
+}
+
+; CHECK-LABEL: hint_undefined
+; CHECK: hint #0x8
+