diff --git a/llvm/include/llvm/CodeGen/ISDOpcodes.h b/llvm/include/llvm/CodeGen/ISDOpcodes.h
--- a/llvm/include/llvm/CodeGen/ISDOpcodes.h
+++ b/llvm/include/llvm/CodeGen/ISDOpcodes.h
@@ -1086,6 +1086,10 @@
   /// known nonzero constant. The only operand here is the chain.
   GET_DYNAMIC_AREA_OFFSET,
 
+  /// Pseudo probe for AutoFDO, as a place holder in a basic block to improve
+  /// the sample counts quality.
+  PSEUDO_PROBE,
+
   /// VSCALE(IMM) - Returns the runtime scaling factor used to calculate the
   /// number of elements within a scalable vector. IMM is a constant integer
   /// multiplier that is applied to the runtime value.
diff --git a/llvm/include/llvm/CodeGen/MachineInstr.h b/llvm/include/llvm/CodeGen/MachineInstr.h
--- a/llvm/include/llvm/CodeGen/MachineInstr.h
+++ b/llvm/include/llvm/CodeGen/MachineInstr.h
@@ -1241,6 +1241,7 @@
     case TargetOpcode::DBG_LABEL:
     case TargetOpcode::LIFETIME_START:
     case TargetOpcode::LIFETIME_END:
+    case TargetOpcode::PSEUDO_PROBE:
       return true;
     }
   }
diff --git a/llvm/include/llvm/CodeGen/SelectionDAG.h b/llvm/include/llvm/CodeGen/SelectionDAG.h
--- a/llvm/include/llvm/CodeGen/SelectionDAG.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAG.h
@@ -1169,6 +1169,11 @@
   SDValue getLifetimeNode(bool IsStart, const SDLoc &dl, SDValue Chain,
                           int FrameIndex, int64_t Size, int64_t Offset = -1);
 
+  /// Creates a PseudoProbeSDNode with function GUID `Guid` and
+  /// the index of the block `Index` it is probing.
+  SDValue getPseudoProbeNode(const SDLoc &Dl, SDValue Chain, uint64_t Guid,
+                             uint64_t Index);
+
   /// Create a MERGE_VALUES node from the given operands.
   SDValue getMergeValues(ArrayRef<SDValue> Ops, const SDLoc &dl);
 
diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
--- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -1794,6 +1794,29 @@
   }
 };
 
+/// This SDNode is used for PSEUDO_PROBE values, which are the function guid and
+/// the index of the basic block being probed. A pseudo probe serves as a place
+/// holder and will be removed at the end of compilation. It does not have any
+/// operand because we do not want the instruction selection to deal with any.
+class PseudoProbeSDNode : public SDNode {
+  friend class SelectionDAG;
+  uint64_t Guid;
+  uint64_t Index;
+
+  PseudoProbeSDNode(unsigned Opcode, unsigned Order, const DebugLoc &Dl,
+                    SDVTList VTs, uint64_t Guid, uint64_t Index)
+      : SDNode(Opcode, Order, Dl, VTs), Guid(Guid), Index(Index) {}
+
+public:
+  int64_t getGuid() const { return Guid; }
+  uint64_t getIndex() const { return Index; }
+
+  // Methods to support isa and dyn_cast
+  static bool classof(const SDNode *N) {
+    return N->getOpcode() == ISD::PSEUDO_PROBE;
+  }
+};
+
 class JumpTableSDNode : public SDNode {
   friend class SelectionDAG;
 
diff --git a/llvm/include/llvm/Support/TargetOpcodes.def b/llvm/include/llvm/Support/TargetOpcodes.def
--- a/llvm/include/llvm/Support/TargetOpcodes.def
+++ b/llvm/include/llvm/Support/TargetOpcodes.def
@@ -106,6 +106,9 @@
 HANDLE_TARGET_OPCODE(LIFETIME_START)
 HANDLE_TARGET_OPCODE(LIFETIME_END)
 
+/// Pseudo probe
+HANDLE_TARGET_OPCODE(PSEUDO_PROBE)
+
 /// A Stackmap instruction captures the location of live variables at its
 /// position in the instruction stream. It is followed by a shadow of bytes
 /// that must lie within the function and not contain another stackmap.
diff --git a/llvm/include/llvm/Target/Target.td b/llvm/include/llvm/Target/Target.td
--- a/llvm/include/llvm/Target/Target.td
+++ b/llvm/include/llvm/Target/Target.td
@@ -1139,6 +1139,13 @@
   let AsmString = "LIFETIME_END";
   let hasSideEffects = 0;
 }
+def PSEUDO_PROBE : StandardPseudoInstruction {
+  let OutOperandList = (outs);
+  let InOperandList = (ins i64imm:$guid, i64imm:$index, i64imm:$type);
+  let AsmString = "PSEUDO_PROBE";
+  let hasSideEffects = 1;
+}
+
 def STACKMAP : StandardPseudoInstruction {
   let OutOperandList = (outs);
   let InOperandList = (ins i64imm:$id, i32imm:$nbytes, variable_ops);
diff --git a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -1082,6 +1082,18 @@
     break;
   }
 
+  case ISD::PSEUDO_PROBE: {
+    unsigned TarOp = TargetOpcode::PSEUDO_PROBE;
+    auto Guid = cast<PseudoProbeSDNode>(Node)->getGuid();
+    auto Index = cast<PseudoProbeSDNode>(Node)->getIndex();
+
+    BuildMI(*MBB, InsertPos, Node->getDebugLoc(), TII->get(TarOp))
+        .addImm(Guid)
+        .addImm(Index)
+        .addImm(0); // 0 for block probes
+    break;
+  }
+
   case ISD::INLINEASM:
   case ISD::INLINEASM_BR: {
     unsigned NumOps = Node->getNumOperands();
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -537,6 +537,10 @@
       ID.AddInteger(cast<LifetimeSDNode>(N)->getOffset());
     }
     break;
+  case ISD::PSEUDO_PROBE:
+    ID.AddInteger(cast<PseudoProbeSDNode>(N)->getGuid());
+    ID.AddInteger(cast<PseudoProbeSDNode>(N)->getIndex());
+    break;
   case ISD::JumpTable:
   case ISD::TargetJumpTable:
     ID.AddInteger(cast<JumpTableSDNode>(N)->getIndex());
@@ -6898,6 +6902,30 @@
   return V;
 }
 
+SDValue SelectionDAG::getPseudoProbeNode(const SDLoc &Dl, SDValue Chain,
+                                         uint64_t Guid, uint64_t Index) {
+
+  const unsigned Opcode = ISD::PSEUDO_PROBE;
+  const auto VTs = getVTList(MVT::Other);
+  SDValue Ops[] = {Chain};
+  FoldingSetNodeID ID;
+  AddNodeIDNode(ID, Opcode, VTs, Ops);
+  ID.AddInteger(Guid);
+  ID.AddInteger(Index);
+  void *IP = nullptr;
+  if (SDNode *E = FindNodeOrInsertPos(ID, Dl, IP))
+    return SDValue(E, 0);
+
+  auto *N = newSDNode<PseudoProbeSDNode>(Opcode, Dl.getIROrder(),
+                                         Dl.getDebugLoc(), VTs, Guid, Index);
+  createOperands(N, Ops);
+  CSEMap.InsertNode(N, IP);
+  InsertNode(N);
+  SDValue V(N, 0);
+  NewSDValueDbgMsg(V, "Creating new node: ", this);
+  return V;
+}
+
 /// InferPointerInfo - If the specified ptr/offset is a frame index, infer a
 /// MachinePointerInfo record from it.  This is particularly useful because the
 /// code generator has many cases where it doesn't bother passing in a
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6615,6 +6615,13 @@
     }
     return;
   }
+  case Intrinsic::pseudoprobe: {
+    auto Guid = cast<ConstantInt>(I.getArgOperand(0))->getZExtValue();
+    auto Index = cast<ConstantInt>(I.getArgOperand(1))->getZExtValue();
+    Res = DAG.getPseudoProbeNode(sdl, getRoot(), Guid, Index);
+    DAG.setRoot(Res);
+    return;
+  }
   case Intrinsic::invariant_start:
     // Discard region information.
     setValue(&I, DAG.getUNDEF(TLI.getPointerTy(DAG.getDataLayout())));
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -394,6 +394,8 @@
   case ISD::DEBUGTRAP:                  return "debugtrap";
   case ISD::LIFETIME_START:             return "lifetime.start";
   case ISD::LIFETIME_END:               return "lifetime.end";
+  case ISD::PSEUDO_PROBE:
+    return "pseudoprobe";
   case ISD::GC_TRANSITION_START:        return "gc_transition.start";
   case ISD::GC_TRANSITION_END:          return "gc_transition.end";
   case ISD::GET_DYNAMIC_AREA_OFFSET:    return "get.dynamic.area.offset";
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2792,6 +2792,7 @@
   case ISD::ANNOTATION_LABEL:
   case ISD::LIFETIME_START:
   case ISD::LIFETIME_END:
+  case ISD::PSEUDO_PROBE:
     NodeToMatch->setNodeId(-1); // Mark selected.
     return;
   case ISD::AssertSext:
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe.mir b/llvm/test/Transforms/SampleProfile/pseudo-probe.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe.mir
@@ -0,0 +1,29 @@
+
+# REQUIRES: x86-registered-target
+# Ensure llc can read and parse MIR pseudo probe operations.
+# RUN: llc -O0 -mtriple x86_64-- -run-pass none %s -o - | FileCheck %s
+
+# CHECK: PSEUDO_PROBE 6699318081062747564, 1, 0
+# CHECK: PSEUDO_PROBE 6699318081062747564, 3, 0
+# CHECK: PSEUDO_PROBE 6699318081062747564, 4, 0
+# CHECK: PSEUDO_PROBE 6699318081062747564, 2, 0
+# CHECK: PSEUDO_PROBE 6699318081062747564, 4, 0
+
+name:            foo
+body:             |
+  bb.0:
+    TEST32rr killed renamable $edi, renamable $edi, implicit-def $eflags
+    PSEUDO_PROBE 6699318081062747564, 1, 0
+    JCC_1 %bb.1, 4, implicit $eflags
+  
+  bb.2:
+    PSEUDO_PROBE 6699318081062747564, 3, 0
+    PSEUDO_PROBE 6699318081062747564, 4, 0
+    RETQ
+  
+  bb.1:
+    PSEUDO_PROBE 6699318081062747564, 2, 0
+    PSEUDO_PROBE 6699318081062747564, 4, 0
+    RETQ
+
+...