diff --git a/llvm/lib/CodeGen/MIRParser/MILexer.h b/llvm/lib/CodeGen/MIRParser/MILexer.h
--- a/llvm/lib/CodeGen/MIRParser/MILexer.h
+++ b/llvm/lib/CodeGen/MIRParser/MILexer.h
@@ -120,6 +120,7 @@
     kw_shufflemask,
     kw_pre_instr_symbol,
     kw_post_instr_symbol,
+    kw_heap_alloc_marker,
     kw_unknown_size,
 
     // Named metadata keywords
diff --git a/llvm/lib/CodeGen/MIRParser/MILexer.cpp b/llvm/lib/CodeGen/MIRParser/MILexer.cpp
--- a/llvm/lib/CodeGen/MIRParser/MILexer.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MILexer.cpp
@@ -252,6 +252,7 @@
       .Case("shufflemask", MIToken::kw_shufflemask)
       .Case("pre-instr-symbol", MIToken::kw_pre_instr_symbol)
       .Case("post-instr-symbol", MIToken::kw_post_instr_symbol)
+      .Case("heap-alloc-marker", MIToken::kw_heap_alloc_marker)
       .Case("unknown-size", MIToken::kw_unknown_size)
       .Default(MIToken::Identifier);
 }
@@ -582,8 +583,8 @@
       .Default(MIToken::Error);
 }
 
-static Cursor maybeLexExlaim(Cursor C, MIToken &Token,
-                             ErrorCallbackType ErrorCallback) {
+static Cursor maybeLexExclaim(Cursor C, MIToken &Token,
+                              ErrorCallbackType ErrorCallback) {
   if (C.peek() != '!')
     return None;
   auto Range = C;
@@ -719,7 +720,7 @@
     return R.remaining();
   if (Cursor R = maybeLexNumericalLiteral(C, Token))
     return R.remaining();
-  if (Cursor R = maybeLexExlaim(C, Token, ErrorCallback))
+  if (Cursor R = maybeLexExclaim(C, Token, ErrorCallback))
     return R.remaining();
   if (Cursor R = maybeLexSymbol(C, Token))
     return R.remaining();
diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -471,6 +471,7 @@
   bool parseOptionalAtomicOrdering(AtomicOrdering &Order);
   bool parseMachineMemoryOperand(MachineMemOperand *&Dest);
   bool parsePreOrPostInstrSymbol(MCSymbol *&Symbol);
+  bool parseHeapAllocMarker(MDNode *&Node);
 
 private:
   /// Convert the integer literal in the current token into an unsigned integer.
@@ -906,6 +907,7 @@
   // Parse the remaining machine operands.
   while (!Token.isNewlineOrEOF() && Token.isNot(MIToken::kw_pre_instr_symbol) &&
          Token.isNot(MIToken::kw_post_instr_symbol) &&
+         Token.isNot(MIToken::kw_heap_alloc_marker) &&
          Token.isNot(MIToken::kw_debug_location) &&
          Token.isNot(MIToken::coloncolon) && Token.isNot(MIToken::lbrace)) {
     auto Loc = Token.location();
@@ -932,6 +934,10 @@
   if (Token.is(MIToken::kw_post_instr_symbol))
     if (parsePreOrPostInstrSymbol(PostInstrSymbol))
       return true;
+  MDNode *HeapAllocMarker = nullptr;
+  if (Token.is(MIToken::kw_heap_alloc_marker))
+    if (parseHeapAllocMarker(HeapAllocMarker))
+      return true;
 
   DebugLoc DebugLocation;
   if (Token.is(MIToken::kw_debug_location)) {
@@ -985,6 +991,8 @@
     MI->setPreInstrSymbol(MF, PreInstrSymbol);
   if (PostInstrSymbol)
     MI->setPostInstrSymbol(MF, PostInstrSymbol);
+  if (HeapAllocMarker)
+    MI->setHeapAllocMarker(MF, HeapAllocMarker);
   if (!MemOperands.empty())
     MI->setMemRefs(MF, MemOperands);
   return false;
@@ -2956,6 +2964,22 @@
   return false;
 }
 
+bool MIParser::parseHeapAllocMarker(MDNode *&Node) {
+  assert(Token.is(MIToken::kw_heap_alloc_marker) &&
+         "Invalid token for a heap alloc marker!");
+  lex();
+  parseMDNode(Node);
+  if (!Node)
+    return error("expected a MDNode after 'heap-alloc-marker'");
+  if (Token.isNewlineOrEOF() || Token.is(MIToken::coloncolon) ||
+      Token.is(MIToken::lbrace))
+    return false;
+  if (Token.isNot(MIToken::comma))
+    return error("expected ',' before the next machine operand");
+  lex();
+  return false;
+}
+
 static void initSlots2BasicBlocks(
     const Function &F,
     DenseMap<unsigned, const BasicBlock *> &Slots2BasicBlocks) {
diff --git a/llvm/lib/CodeGen/MIRPrinter.cpp b/llvm/lib/CodeGen/MIRPrinter.cpp
--- a/llvm/lib/CodeGen/MIRPrinter.cpp
+++ b/llvm/lib/CodeGen/MIRPrinter.cpp
@@ -784,6 +784,13 @@
     MachineOperand::printSymbol(OS, *PostInstrSymbol);
     NeedComma = true;
   }
+  if (MDNode *HeapAllocMarker = MI.getHeapAllocMarker()) {
+    if (NeedComma)
+      OS << ',';
+    OS << " heap-alloc-marker ";
+    HeapAllocMarker->printAsOperand(OS, MST);
+    NeedComma = true;
+  }
 
   if (const DebugLoc &DL = MI.getDebugLoc()) {
     if (NeedComma)
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
@@ -1701,12 +1701,13 @@
     OS << " post-instr-symbol ";
     MachineOperand::printSymbol(OS, *PostInstrSymbol);
   }
-  if (/*MDNode *HeapAllocMarker =*/getHeapAllocMarker()) {
+  if (MDNode *HeapAllocMarker = getHeapAllocMarker()) {
     if (!FirstOp) {
       FirstOp = false;
       OS << ',';
     }
-    OS << " heap-alloc-marker";
+    OS << " heap-alloc-marker ";
+    HeapAllocMarker->printAsOperand(OS, MST);
   }
 
   if (!SkipDebugLoc) {
diff --git a/llvm/test/CodeGen/MIR/X86/instr-heap-alloc-operands.mir b/llvm/test/CodeGen/MIR/X86/instr-heap-alloc-operands.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/X86/instr-heap-alloc-operands.mir
@@ -0,0 +1,42 @@
+# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# This test ensures that the MIR parser parses heap alloc markers correctly.
+
+--- |
+  declare i8* @f(i32) nounwind
+
+  define i32 @test(i32 %x) nounwind {
+  entry:
+    call i8* @f(i32 %x), !heapallocsite !2
+    ret i32 undef
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+  !1 = !DIFile(filename: "test.ll", directory: "")
+  !2 = !{}
+  !3 = !{i32 2, !"Debug Info Version", i32 3}
+  !4 = !{i32 1, !"wchar_size", i32 2}
+
+...
+---
+name: test
+# CHECK-LABEL: name: test
+tracksRegLiveness: true
+frameInfo:
+  hasCalls: true
+body: |
+  bb.0.entry:
+    liveins: $ecx
+
+    %0:gr32 = COPY $ecx
+    ADJCALLSTACKDOWN64 32, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    $ecx = COPY %0
+    CALL64pcrel32 @f, csr_win64, implicit $rsp, implicit $ssp, implicit $ecx, implicit-def $rsp, implicit-def $ssp, implicit-def dead $rax, heap-alloc-marker !2
+  ; CHECK: CALL64pcrel32 @f, {{.*}} heap-alloc-marker !2
+    ADJCALLSTACKUP64 32, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp
+    $eax = MOV32r0 implicit-def dead $eflags
+    RET 0, killed $eax
+
+...
diff --git a/llvm/test/CodeGen/X86/heap-alloc-markers.mir b/llvm/test/CodeGen/X86/heap-alloc-markers.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/heap-alloc-markers.mir
@@ -0,0 +1,50 @@
+# RUN: llc -mtriple=x86_64-unknown-windows-msvc -start-before=x86-flags-copy-lowering -o - %s | FileCheck %s
+#
+# Test the emission of heap alloc site instruction labels.
+
+--- |
+  declare i8* @alloc(i32) nounwind
+
+  define i32 @test(i32 %x) nounwind !dbg !6 {
+  entry:
+    call i8* @alloc(i32 %x), !dbg !11, !heapallocsite !2
+    ret i32 0, !dbg !12
+  }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4, !5}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+  !1 = !DIFile(filename: "<stdin>", directory: "")
+  !2 = !{}
+  !3 = !{i32 2, !"CodeView", i32 1}
+  !4 = !{i32 2, !"Debug Info Version", i32 3}
+  !5 = !{i32 1, !"wchar_size", i32 2}
+  !6 = distinct !DISubprogram(name: "test", scope: !7, file: !7, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+  !7 = !DIFile(filename: "test.c", directory: "")
+  !8 = !DISubroutineType(types: !9)
+  !9 = !{!10, !10}
+  !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !11 = !DILocation(line: 3, scope: !6)
+  !12 = !DILocation(line: 4, scope: !6)
+
+...
+---
+name: test
+# CHECK-LABEL: {{^}}test:
+tracksRegLiveness: true
+frameInfo:
+  hasCalls: true
+body: |
+  bb.0.entry:
+    liveins: $ecx
+
+    ADJCALLSTACKDOWN64 32, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !11
+    CALL64pcrel32 @alloc, csr_win64, implicit $rsp, implicit $ssp, implicit $ecx, implicit-def $rsp, implicit-def $ssp, implicit-def dead $rax, heap-alloc-marker !2, debug-location !11
+  ; CHECK:      callq alloc
+  ; CHECK-NEXT: .Ltmp{{.*}}:
+    ADJCALLSTACKUP64 32, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp, debug-location !11
+    $eax = MOV32r0 implicit-def dead $eflags, debug-location !12
+    RET 0, killed $eax, debug-location !12
+
+...