Index: include/llvm/IR/IntrinsicsX86.td
===================================================================
--- include/llvm/IR/IntrinsicsX86.td
+++ include/llvm/IR/IntrinsicsX86.td
@@ -6421,3 +6421,10 @@
   def int_x86_clzero : GCCBuiltin<"__builtin_ia32_clzero">,
       Intrinsic<[], [llvm_ptr_ty], []>;
 }
+
+//===----------------------------------------------------------------------===//
+// Cache-line demote
+let TargetPrefix = "x86" in {
+  def int_x86_cldemote : GCCBuiltin<"__builtin_ia32_cldemote">,
+      Intrinsic<[], [llvm_ptr_ty], []>;
+}
Index: lib/Support/Host.cpp
===================================================================
--- lib/Support/Host.cpp
+++ lib/Support/Host.cpp
@@ -1254,6 +1254,7 @@
   Features["avx512bitalg"]    = HasLeaf7 && ((ECX >> 12) & 1) && HasAVX512Save;
   Features["avx512vpopcntdq"] = HasLeaf7 && ((ECX >> 14) & 1) && HasAVX512Save;
   Features["rdpid"]           = HasLeaf7 && ((ECX >> 22) & 1);
+  Features["cldemote"]        = HasLeaf7 && ((ECX >> 25) & 1);
 
   Features["ibt"] = HasLeaf7 && ((EDX >> 20) & 1);
 
Index: lib/Target/X86/X86.td
===================================================================
--- lib/Target/X86/X86.td
+++ lib/Target/X86/X86.td
@@ -230,6 +230,8 @@
                                       "Enable MONITORX/MWAITX timer functionality">;
 def FeatureCLZERO  : SubtargetFeature<"clzero", "HasCLZERO", "true",
                                       "Enable Cache Line Zero">;
+def FeatureCLDEMOTE  : SubtargetFeature<"cldemote", "HasCLDEMOTE", "true",
+                                      "Enable Cache Demote">;
 def FeatureMPX     : SubtargetFeature<"mpx", "HasMPX", "true",
                                       "Support MPX instructions">;
 def FeatureLEAForSP : SubtargetFeature<"lea-sp", "UseLeaForSP", "true",
Index: lib/Target/X86/X86InstrInfo.td
===================================================================
--- lib/Target/X86/X86InstrInfo.td
+++ lib/Target/X86/X86InstrInfo.td
@@ -881,6 +881,7 @@
 def HasLAHFSAHF  : Predicate<"Subtarget->hasLAHFSAHF()">;
 def HasMWAITX    : Predicate<"Subtarget->hasMWAITX()">;
 def HasCLZERO    : Predicate<"Subtarget->hasCLZERO()">;
+def HasCLDEMOTE  : Predicate<"Subtarget->hasCLDEMOTE()">;
 def FPStackf32   : Predicate<"!Subtarget->hasSSE1()">;
 def FPStackf64   : Predicate<"!Subtarget->hasSSE2()">;
 def HasMPX       : Predicate<"Subtarget->hasMPX()">;
@@ -2758,6 +2759,9 @@
 def CLWB       : I<0xAE, MRM6m, (outs), (ins i8mem:$src), "clwb\t$src",
                    [(int_x86_clwb addr:$src)], IIC_SSE_PREFETCH>, PD;
 
+def CLDEMOTE : I<0x1C, MRM0m, (outs), (ins i8mem:$src), "cldemote\t$src",
+                   [(int_x86_cldemote addr:$src)]>, TB, Requires<[HasCLDEMOTE]>;
+
 //===----------------------------------------------------------------------===//
 // Subsystems.
 //===----------------------------------------------------------------------===//
Index: lib/Target/X86/X86Subtarget.h
===================================================================
--- lib/Target/X86/X86Subtarget.h
+++ lib/Target/X86/X86Subtarget.h
@@ -204,6 +204,9 @@
   /// Processor has Cache Line Zero instruction
   bool HasCLZERO;
 
+  /// Processor has Cache Line Demote instruction
+  bool HasCLDEMOTE;
+
   /// Processor has Prefetch with intent to Write instruction
   bool HasPREFETCHWT1;
 
@@ -573,6 +576,7 @@
   bool hasLAHFSAHF() const { return HasLAHFSAHF; }
   bool hasMWAITX() const { return HasMWAITX; }
   bool hasCLZERO() const { return HasCLZERO; }
+  bool hasCLDEMOTE() const { return HasCLDEMOTE; }
   bool isSHLDSlow() const { return IsSHLDSlow; }
   bool isPMULLDSlow() const { return IsPMULLDSlow; }
   bool isUnalignedMem16Slow() const { return IsUAMem16Slow; }
Index: lib/Target/X86/X86Subtarget.cpp
===================================================================
--- lib/Target/X86/X86Subtarget.cpp
+++ lib/Target/X86/X86Subtarget.cpp
@@ -318,6 +318,7 @@
   HasLAHFSAHF = false;
   HasMWAITX = false;
   HasCLZERO = false;
+  HasCLDEMOTE = false;
   HasMPX = false;
   HasSHSTK = false;
   HasIBT = false;
Index: test/CodeGen/X86/cldemote-intrinsic.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/cldemote-intrinsic.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-linux -mattr=+cldemote | FileCheck %s --check-prefix=X64
+; RUN: llc < %s -mtriple=i386-pc-linux -mattr=+cldemote | FileCheck %s --check-prefix=X32
+
+define void @test_cldemote(i8* %p) {
+; X64-LABEL: test_cldemote:
+; X64:       # %bb.0: # %entry
+; X64-NEXT:    cldemote (%rdi)
+; X64-NEXT:    retq
+;
+; X32-LABEL: test_cldemote:
+; X32:       # %bb.0: # %entry
+; X32-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X32-NEXT:    cldemote (%eax)
+; X32-NEXT:    retl
+entry:
+  tail call void @llvm.x86.cldemote(i8* %p)
+  ret void
+}
+
+declare void @llvm.x86.cldemote(i8*)
Index: test/MC/Disassembler/X86/x86-32.txt
===================================================================
--- test/MC/Disassembler/X86/x86-32.txt
+++ test/MC/Disassembler/X86/x86-32.txt
@@ -820,3 +820,9 @@
 
 # CHECK: ptwritel %eax
 0xf3 0x0f 0xae 0xe0
+
+# CHECK: cldemote 4(%eax)
+0x0f 0x1c 0x40 0x04
+
+# CHECK: cldemote -559038737(%ebx,%ecx,8)
+0x0f,0x1c,0x84,0xcb,0xef,0xbe,0xad,0xde
Index: test/MC/Disassembler/X86/x86-64.txt
===================================================================
--- test/MC/Disassembler/X86/x86-64.txt
+++ test/MC/Disassembler/X86/x86-64.txt
@@ -516,3 +516,9 @@
 
 # CHECK: ptwriteq %rax
 0xf3 0x48 0x0f 0xae 0xe0
+
+# CHECK: cldemote 4(%rax)
+0x0f 0x1c 0x40 0x04
+
+# CHECK: cldemote -559038737(%rbx,%rcx,8)
+0x0f,0x1c,0x84,0xcb,0xef,0xbe,0xad,0xde
Index: test/MC/X86/x86-32-coverage.s
===================================================================
--- test/MC/X86/x86-32-coverage.s
+++ test/MC/X86/x86-32-coverage.s
@@ -10741,3 +10741,10 @@
 // CHECK:  encoding: [0xf0,0x01,0x37]
         	lock add %esi, (%edi)
 
+// CHECK: cldemote 4(%eax)
+// CHECK:  encoding: [0x0f,0x1c,0x40,0x04]
+        	cldemote 4(%eax)
+
+// CHECK: cldemote 3735928559(%ebx,%ecx,8)
+// CHECK:  encoding: [0x0f,0x1c,0x84,0xcb,0xef,0xbe,0xad,0xde]
+        	cldemote 0xdeadbeef(%ebx,%ecx,8)
Index: test/MC/X86/x86-64.s
===================================================================
--- test/MC/X86/x86-64.s
+++ test/MC/X86/x86-64.s
@@ -1559,6 +1559,14 @@
 // CHECK:  encoding: [0xf3,0x48,0x0f,0xae,0xe0]
 ptwriteq %rax
 
+// CHECK: cldemote 4(%rax)
+// CHECK:  encoding: [0x0f,0x1c,0x40,0x04]
+cldemote 4(%rax)
+
+// CHECK: cldemote 3735928559(%rbx,%rcx,8)
+// CHECK:  encoding: [0x0f,0x1c,0x84,0xcb,0xef,0xbe,0xad,0xde]
+cldemote 0xdeadbeef(%rbx,%rcx,8)
+
 //  __asm __volatile(
 //    "pushf        \n\t"
 //    "popf       \n\t"