Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -1543,8 +1543,8 @@
     trap or generate asynchronous exceptions. Exception handling schemes
     that are recognized by LLVM to handle asynchronous exceptions, such
     as SEH, will still provide their implementation defined semantics.
-``"null-pointer-is-valid"``
-   If ``"null-pointer-is-valid"`` is set to ``"true"``, then ``null`` address
+``null_pointer_is_valid``
+   If ``null_pointer_is_valid`` is set, then the ``null`` address
    in address-space 0 is considered to be a valid address for memory loads and
    stores. Any analysis or optimization should not treat dereferencing a
    pointer to ``null`` as undefined behavior in this function.
Index: include/llvm/Bitcode/LLVMBitCodes.h
===================================================================
--- include/llvm/Bitcode/LLVMBitCodes.h
+++ include/llvm/Bitcode/LLVMBitCodes.h
@@ -633,6 +633,7 @@
   ATTR_KIND_NOFREE = 62,
   ATTR_KIND_NOSYNC = 63,
   ATTR_KIND_SANITIZE_MEMTAG = 64,
+  ATTR_KIND_NULL_POINTER_IS_VALID = 65,
 };
 
 enum ComdatSelectionKindCodes {
Index: include/llvm/IR/Attributes.td
===================================================================
--- include/llvm/IR/Attributes.td
+++ include/llvm/IR/Attributes.td
@@ -118,6 +118,9 @@
 /// Function doesn't unwind stack.
 def NoUnwind : EnumAttr<"nounwind">;
 
+/// Null pointer in address space zero is valid.
+def NullPointerIsValid : EnumAttr<"null_pointer_is_valid">;
+
 /// Select optimizations for best fuzzing signal.
 def OptForFuzzing : EnumAttr<"optforfuzzing">;
 
Index: include/llvm/IR/AutoUpgrade.h
===================================================================
--- include/llvm/IR/AutoUpgrade.h
+++ include/llvm/IR/AutoUpgrade.h
@@ -92,9 +92,8 @@
   /// pointers.
   std::string UpgradeDataLayoutString(StringRef DL, StringRef Triple);
 
-  /// Upgrade function attributes "no-frame-pointer-elim" and
-  /// "no-frame-pointer-elim-non-leaf" to "frame-pointer".
-  void UpgradeFramePointerAttributes(AttrBuilder &B);
+  /// Upgrade attributes that changed format or kind.
+  void UpgradeAttributes(AttrBuilder &B);
 
 } // End llvm namespace
 
Index: lib/AsmParser/LLLexer.cpp
===================================================================
--- lib/AsmParser/LLLexer.cpp
+++ lib/AsmParser/LLLexer.cpp
@@ -664,6 +664,7 @@
   KEYWORD(nosync);
   KEYWORD(nocf_check);
   KEYWORD(nounwind);
+  KEYWORD(null_pointer_is_valid);
   KEYWORD(optforfuzzing);
   KEYWORD(optnone);
   KEYWORD(optsize);
Index: lib/AsmParser/LLParser.cpp
===================================================================
--- lib/AsmParser/LLParser.cpp
+++ lib/AsmParser/LLParser.cpp
@@ -1312,6 +1312,8 @@
     case lltok::kw_nocf_check: B.addAttribute(Attribute::NoCfCheck); break;
     case lltok::kw_norecurse: B.addAttribute(Attribute::NoRecurse); break;
     case lltok::kw_nounwind: B.addAttribute(Attribute::NoUnwind); break;
+    case lltok::kw_null_pointer_is_valid:
+      B.addAttribute(Attribute::NullPointerIsValid); break;
     case lltok::kw_optforfuzzing:
       B.addAttribute(Attribute::OptForFuzzing); break;
     case lltok::kw_optnone: B.addAttribute(Attribute::OptimizeNone); break;
Index: lib/AsmParser/LLToken.h
===================================================================
--- lib/AsmParser/LLToken.h
+++ lib/AsmParser/LLToken.h
@@ -210,6 +210,7 @@
   kw_nosync,
   kw_nocf_check,
   kw_nounwind,
+  kw_null_pointer_is_valid,
   kw_optforfuzzing,
   kw_optnone,
   kw_optsize,
Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1303,6 +1303,10 @@
   case Attribute::SanitizeMemTag:
     llvm_unreachable("sanitize_memtag attribute not supported in raw format");
     break;
+  case Attribute::NullPointerIsValid:
+    llvm_unreachable(
+        "null_pointer_is_valid attribute not supported in raw format");
+    break;
   }
   llvm_unreachable("Unsupported attribute type");
 }
@@ -1312,7 +1316,8 @@
 
   for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
        I = Attribute::AttrKind(I + 1)) {
-    if (I == Attribute::SanitizeMemTag ||
+    if (I == Attribute::NullPointerIsValid ||
+        I == Attribute::SanitizeMemTag ||
         I == Attribute::Dereferenceable ||
         I == Attribute::DereferenceableOrNull ||
         I == Attribute::ArgMemOnly ||
@@ -1484,6 +1489,8 @@
     return Attribute::NoCfCheck;
   case bitc::ATTR_KIND_NO_UNWIND:
     return Attribute::NoUnwind;
+  case bitc::ATTR_KIND_NULL_POINTER_IS_VALID:
+    return Attribute::NullPointerIsValid;
   case bitc::ATTR_KIND_OPT_FOR_FUZZING:
     return Attribute::OptForFuzzing;
   case bitc::ATTR_KIND_OPTIMIZE_FOR_SIZE:
@@ -1664,7 +1671,7 @@
         }
       }
 
-      UpgradeFramePointerAttributes(B);
+      UpgradeAttributes(B);
       MAttributeGroups[GrpID] = AttributeList::get(Context, Idx, B);
       break;
     }
Index: lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- lib/Bitcode/Writer/BitcodeWriter.cpp
+++ lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -666,6 +666,8 @@
     return bitc::ATTR_KIND_NOCF_CHECK;
   case Attribute::NoUnwind:
     return bitc::ATTR_KIND_NO_UNWIND;
+  case Attribute::NullPointerIsValid:
+    return bitc::ATTR_KIND_NULL_POINTER_IS_VALID;
   case Attribute::OptForFuzzing:
     return bitc::ATTR_KIND_OPT_FOR_FUZZING;
   case Attribute::OptimizeForSize:
Index: lib/CodeGen/CGCall.cpp
===================================================================
--- lib/CodeGen/CGCall.cpp
+++ lib/CodeGen/CGCall.cpp
@@ -1747,7 +1747,7 @@
                            llvm::toStringRef(CodeGenOpts.LessPreciseFPMAD));
 
     if (CodeGenOpts.NullPointerIsValid)
-      FuncAttrs.addAttribute("null-pointer-is-valid", "true");
+      FuncAttrs.addAttribute(llvm::Attribute::NullPointerIsValid);
 
     if (CodeGenOpts.FPDenormalMode != llvm::DenormalMode::getIEEE())
       FuncAttrs.addAttribute("denormal-fp-math",
Index: lib/IR/Attributes.cpp
===================================================================
--- lib/IR/Attributes.cpp
+++ lib/IR/Attributes.cpp
@@ -376,6 +376,8 @@
     return "noreturn";
   if (hasAttribute(Attribute::NoSync))
     return "nosync";
+  if (hasAttribute(Attribute::NullPointerIsValid))
+    return "null_pointer_is_valid";
   if (hasAttribute(Attribute::WillReturn))
     return "willreturn";
   if (hasAttribute(Attribute::NoCfCheck))
@@ -1877,12 +1879,12 @@
   }
 }
 
-/// If the inlined function has "null-pointer-is-valid=true" attribute,
+/// If the inlined function has null_pointer_is_defined attribute,
 /// set this attribute in the caller post inlining.
 static void
 adjustNullPointerValidAttr(Function &Caller, const Function &Callee) {
   if (Callee.nullPointerIsDefined() && !Caller.nullPointerIsDefined()) {
-    Caller.addFnAttr(Callee.getFnAttribute("null-pointer-is-valid"));
+    Caller.addFnAttr(Attribute::NullPointerIsValid);
   }
 }
 
Index: lib/IR/AutoUpgrade.cpp
===================================================================
--- lib/IR/AutoUpgrade.cpp
+++ lib/IR/AutoUpgrade.cpp
@@ -4245,7 +4245,7 @@
   return Res;
 }
 
-void llvm::UpgradeFramePointerAttributes(AttrBuilder &B) {
+void llvm::UpgradeAttributes(AttrBuilder &B) {
   StringRef FramePointer;
   if (B.contains("no-frame-pointer-elim")) {
     // The value can be "true" or "false".
@@ -4260,7 +4260,17 @@
       FramePointer = "non-leaf";
     B.removeAttribute("no-frame-pointer-elim-non-leaf");
   }
-
   if (!FramePointer.empty())
     B.addAttribute("frame-pointer", FramePointer);
+
+  if (B.contains("null-pointer-is-valid")) {
+    // The value can be "true" or "false".
+    bool NullPointerIsValid = false;
+    for (const auto &I : B.td_attrs())
+      if (I.first == "null-pointer-is-valid")
+        NullPointerIsValid = I.second == "true";
+    B.removeAttribute("null-pointer-is-valid");
+    if (NullPointerIsValid)
+      B.addAttribute(Attribute::NullPointerIsValid);
+  }
 }
Index: lib/IR/Function.cpp
===================================================================
--- lib/IR/Function.cpp
+++ lib/IR/Function.cpp
@@ -1634,9 +1634,7 @@
 }
 
 bool Function::nullPointerIsDefined() const {
-  return getFnAttribute("null-pointer-is-valid")
-          .getValueAsString()
-          .equals("true");
+  return hasFnAttribute(Attribute::NullPointerIsValid);
 }
 
 bool llvm::NullPointerIsDefined(const Function *F, unsigned AS) {
Index: lib/IR/Verifier.cpp
===================================================================
--- lib/IR/Verifier.cpp
+++ lib/IR/Verifier.cpp
@@ -1552,6 +1552,7 @@
   case Attribute::SpeculativeLoadHardening:
   case Attribute::Speculatable:
   case Attribute::StrictFP:
+  case Attribute::NullPointerIsValid:
     return true;
   default:
     break;
Index: lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- lib/Transforms/Utils/CodeExtractor.cpp
+++ lib/Transforms/Utils/CodeExtractor.cpp
@@ -903,6 +903,7 @@
       case Attribute::NonLazyBind:
       case Attribute::NoRedZone:
       case Attribute::NoUnwind:
+      case Attribute::NullPointerIsValid:
       case Attribute::OptForFuzzing:
       case Attribute::OptimizeNone:
       case Attribute::OptimizeForSize:
Index: test/Bitcode/attributes.ll
===================================================================
--- test/Bitcode/attributes.ll
+++ test/Bitcode/attributes.ll
@@ -374,6 +374,12 @@
   ret void;
 }
 
+; CHECK: define void @f64() #40
+define void @f64() null_pointer_is_valid
+{
+  ret void;
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -414,4 +420,5 @@
 ; CHECK: attributes #37 = { nofree }
 ; CHECK: attributes #38 = { nosync }
 ; CHECK: attributes #39 = { sanitize_memtag }
-; CHECK: attributes #40 = { nobuiltin }
+; CHECK: attributes #40 = { null_pointer_is_valid }
+; CHECK: attributes #41 = { nobuiltin }
Index: test/CodeGen/delete-null-pointer-checks.c
===================================================================
--- test/CodeGen/delete-null-pointer-checks.c
+++ test/CodeGen/delete-null-pointer-checks.c
@@ -16,5 +16,5 @@
   return *Q;
 }
 
-// NULL-POINTER-INVALID-NOT: attributes #0 = {{.*}} "null-pointer-is-valid"="true"
-// NULL-POINTER-VALID: attributes #0 = {{.*}} "null-pointer-is-valid"="true"
+// NULL-POINTER-INVALID-NOT: attributes #0 = {{.*}} null_pointer_is_valid
+// NULL-POINTER-VALID: attributes #0 = {{.*}} null_pointer_is_valid