Index: llvm/include/llvm/AsmParser/LLParser.h
===================================================================
--- llvm/include/llvm/AsmParser/LLParser.h
+++ llvm/include/llvm/AsmParser/LLParser.h
@@ -47,6 +47,7 @@
       t_LocalName, t_GlobalName,       // Name in StrVal.
       t_APSInt, t_APFloat,             // Value in APSIntVal/APFloatVal.
       t_Null, t_Undef, t_Zero, t_None, t_Poison, // No value.
+      t_UnknownProvenance,             // No value.
       t_EmptyArray,                    // No value:  []
       t_Constant,                      // Value in ConstantVal.
       t_InlineAsm,                     // Value in FTy/StrVal/StrVal2/UIntVal.
Index: llvm/include/llvm/AsmParser/LLToken.h
===================================================================
--- llvm/include/llvm/AsmParser/LLToken.h
+++ llvm/include/llvm/AsmParser/LLToken.h
@@ -91,6 +91,7 @@
   kw_deplibs, // FIXME: Remove in 4.0
   kw_datalayout,
   kw_volatile,
+  kw_unknown_provenance,
   kw_atomic,
   kw_unordered,
   kw_monotonic,
Index: llvm/lib/AsmParser/LLLexer.cpp
===================================================================
--- llvm/lib/AsmParser/LLLexer.cpp
+++ llvm/lib/AsmParser/LLLexer.cpp
@@ -545,6 +545,7 @@
   KEYWORD(unwind);
   KEYWORD(datalayout);
   KEYWORD(volatile);
+  KEYWORD(unknown_provenance);
   KEYWORD(atomic);
   KEYWORD(unordered);
   KEYWORD(monotonic);
Index: llvm/lib/AsmParser/LLParser.cpp
===================================================================
--- llvm/lib/AsmParser/LLParser.cpp
+++ llvm/lib/AsmParser/LLParser.cpp
@@ -3023,6 +3023,7 @@
     break;
   case lltok::kw_null: ID.Kind = ValID::t_Null; break;
   case lltok::kw_undef: ID.Kind = ValID::t_Undef; break;
+  case lltok::kw_unknown_provenance: ID.Kind = ValID::t_UnknownProvenance; break;
   case lltok::kw_poison: ID.Kind = ValID::t_Poison; break;
   case lltok::kw_zeroinitializer: ID.Kind = ValID::t_Zero; break;
   case lltok::kw_none: ID.Kind = ValID::t_None; break;
@@ -5315,6 +5316,11 @@
       return error(ID.Loc, "invalid type for undef constant");
     V = UndefValue::get(Ty);
     return false;
+  case ValID::t_UnknownProvenance:
+    if (!Ty->isPointerTy())
+      return error(ID.Loc, "unknown_provenance must be a pointer type");
+    V = UnknownProvenance::get(cast<PointerType>(Ty));
+    return false;
   case ValID::t_EmptyArray:
     if (!Ty->isArrayTy() || cast<ArrayType>(Ty)->getNumElements() != 0)
       return error(ID.Loc, "invalid empty array initializer");
Index: llvm/lib/IR/AsmWriter.cpp
===================================================================
--- llvm/lib/IR/AsmWriter.cpp
+++ llvm/lib/IR/AsmWriter.cpp
@@ -1581,6 +1581,11 @@
     return;
   }
 
+  if (isa<UnknownProvenance>(CV)) {
+    Out << "unknown_provenance";
+    return;
+  }
+
   if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(CV)) {
     Out << CE->getOpcodeName();
     WriteOptimizationInfo(Out, CE);