diff --git a/llvm/lib/CodeGen/LiveRangeShrink.cpp b/llvm/lib/CodeGen/LiveRangeShrink.cpp
--- a/llvm/lib/CodeGen/LiveRangeShrink.cpp
+++ b/llvm/lib/CodeGen/LiveRangeShrink.cpp
@@ -156,7 +156,8 @@
         // If MI has side effects, it should become a barrier for code motion.
         // IOM is rebuild from the next instruction to prevent later
         // instructions from being moved before this MI.
-        if (MI.hasUnmodeledSideEffects() && Next != MBB.end()) {
+        if (MI.hasUnmodeledSideEffects() && !MI.isPseudoProbe() &&
+            Next != MBB.end()) {
           BuildInstOrderMap(Next, IOM);
           SawStore = false;
         }
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
--- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp
+++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp
@@ -3101,7 +3101,7 @@
 static uint64_t countMBBInstruction(MachineBasicBlock *MBB) {
   uint64_t InstrCount = 0;
   for (MachineInstr &MI : *MBB) {
-    if (!MI.isPHI() && !MI.isMetaInstruction())
+    if (!MI.isPHI() && !MI.isMetaInstruction() && !MI.isPseudoProbe())
       InstrCount += 1;
   }
   return InstrCount;
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -1376,6 +1376,10 @@
       !hasUnmodeledSideEffects())
     return false;
 
+  // A pseudo probe instruction doesn't really have a memory volatile access.
+  if (isPseudoProbe())
+    return false;
+
   // Otherwise, if the instruction has no memory reference information,
   // conservatively assume it wasn't preserved.
   if (memoperands_empty())
@@ -1462,7 +1466,8 @@
 }
 
 bool MachineInstr::isLoadFoldBarrier() const {
-  return mayStore() || isCall() || hasUnmodeledSideEffects();
+  return mayStore() || isCall() ||
+         (hasUnmodeledSideEffects() && !isPseudoProbe());
 }
 
 /// allDefsAreDead - Return true if all the defs of this instruction are dead.
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
@@ -9682,8 +9682,9 @@
       // We will look through cast uses, so ignore them completely.
       if (I.isCast())
         continue;
-      // Ignore debug info intrinsics, they don't escape or store to allocas.
-      if (isa<DbgInfoIntrinsic>(I))
+      // Ignore debug info and pseudo op intrinsics, they don't escape or store
+      // to allocas.
+      if (I.isDebugOrPseudoInst())
         continue;
       // This is an unknown instruction. Assume it escapes or writes to all
       // static alloca operands.
diff --git a/llvm/lib/CodeGen/StackProtector.cpp b/llvm/lib/CodeGen/StackProtector.cpp
--- a/llvm/lib/CodeGen/StackProtector.cpp
+++ b/llvm/lib/CodeGen/StackProtector.cpp
@@ -193,7 +193,7 @@
       // Ignore intrinsics that do not become real instructions.
       // TODO: Narrow this to intrinsics that have store-like effects.
       const auto *CI = cast<CallInst>(I);
-      if (!isa<DbgInfoIntrinsic>(CI) && !CI->isLifetimeStartOrEnd())
+      if (!CI->isDebugOrPseudoInst() && !CI->isLifetimeStartOrEnd())
         return true;
       break;
     }
diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -804,6 +804,9 @@
     // Debug instructions cannot be counted against the limit.
     if (OtherMI.isDebugInstr())
       continue;
+    // Pseudo probe instructions cannot be counted against the limit.
+    if (OtherMI.isPseudoProbe())
+      continue;
     if (NumVisited > 10)  // FIXME: Arbitrary limit to reduce compile time cost.
       return false;
     ++NumVisited;
@@ -977,6 +980,9 @@
     // Debug instructions cannot be counted against the limit.
     if (OtherMI.isDebugInstr())
       continue;
+    // Pseudo probe instructions cannot be counted against the limit.
+    if (OtherMI.isPseudoProbe())
+      continue;
     if (NumVisited > 10)  // FIXME: Arbitrary limit to reduce compile time cost.
       return false;
     ++NumVisited;
diff --git a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
--- a/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -149,6 +149,13 @@
       if (isNoModRef(MRI))
         continue;
 
+      // A pseudo probe call shouldn't change any function attribute since it
+      // doesn't translate to a real instruction. It comes with a memory access
+      // tag to prevent itself being removed by optimizations and not block
+      // other instructions being optimized.
+      if (isa<PseudoProbeInst>(I))
+        continue;
+
       if (!AliasAnalysis::onlyAccessesArgPointees(MRB)) {
         // The call could access any memory. If that includes writes, note it.
         if (isModSet(MRI))
diff --git a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -592,7 +592,7 @@
   BasicBlock::iterator BBI = L->getIterator(), E = L->getParent()->end();
 
   for (++BBI; BBI != E; ++BBI)
-    if (BBI->mayWriteToMemory())
+    if (BBI->mayWriteToMemory() && !isa<PseudoProbeInst>(BBI))
       return false;
 
   // Check for non-address taken alloca.  If not address-taken already, it isn't
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -3878,9 +3878,10 @@
         }
       }
 
-      // Skip processing debug intrinsics in InstCombine. Processing these call instructions
-      // consumes non-trivial amount of time and provides no value for the optimization.
-      if (!isa<DbgInfoIntrinsic>(Inst)) {
+      // Skip processing debug and pseudo intrinsics in InstCombine. Processing
+      // these call instructions consumes non-trivial amount of time and
+      // provides no value for the optimization.
+      if (!Inst->isDebugOrPseudoInst()) {
         InstrsForInstCombineWorklist.push_back(Inst);
         SeenAliasScopes.analyse(Inst);
       }