Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3287,6 +3287,9 @@
 def warn_non_literal_null_pointer : Warning<
     "expression which evaluates to zero treated as a null pointer constant of "
     "type %0">, InGroup<NonLiteralNullConversion>;
+def warn_pointer_compare : Warning<
+  "comparison between NULL and null character">,
+  InGroup<DiagGroup<"pointer-compare">>, DefaultIgnore;
 def warn_impcast_null_pointer_to_integer : Warning<
     "implicit conversion of %select{NULL|nullptr}0 constant to %1">,
     InGroup<NullConversion>;
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -9991,6 +9991,7 @@
   QualType CheckShiftOperands( // C99 6.5.7
     ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
     BinaryOperatorKind Opc, bool IsCompAssign = false);
+  void checkNullCharToNullptr(ExprResult &E); // helper for CheckCompareOperand
   QualType CheckCompareOperands( // C99 6.5.8/9
       ExprResult &LHS, ExprResult &RHS, SourceLocation Loc,
       BinaryOperatorKind Opc);
Index: clang/lib/Sema/SemaExpr.cpp
===================================================================
--- clang/lib/Sema/SemaExpr.cpp
+++ clang/lib/Sema/SemaExpr.cpp
@@ -10433,6 +10433,19 @@
   return S.Context.getLogicalOperationType();
 }
 
+// Purely helper function for CheckCompareOperand.
+void Sema::checkNullCharToNullptr(ExprResult &E) {
+  if (!E.get()->getType()->isAnyPointerType() &&
+      E.get()->isNullPointerConstant(Context, Expr::NPC_ValueDependentIsNotNull) ==
+        Expr::NPCK_ZeroExpression) {
+    if (isa<CharacterLiteral>(E.get())) {
+      const CharacterLiteral *RCL = dyn_cast<CharacterLiteral>(E.get());
+      if (RCL->getValue() == '\0')
+        Diag(E.get()->getExprLoc(), diag::warn_pointer_compare);
+    }
+  }
+}
+
 // C99 6.5.8, C++ [expr.rel]
 QualType Sema::CheckCompareOperands(ExprResult &LHS, ExprResult &RHS,
                                     SourceLocation Loc,
@@ -10466,6 +10479,8 @@
   }
 
   checkArithmeticNull(*this, LHS, RHS, Loc, /*isCompare=*/true);
+  checkNullCharToNullptr(LHS);
+  checkNullCharToNullptr(RHS);
 
   // Handle vector comparisons separately.
   if (LHS.get()->getType()->isVectorType() ||
Index: clang/test/Sema/warn-nullchar-nullptr.c
===================================================================
--- /dev/null
+++ clang/test/Sema/warn-nullchar-nullptr.c
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -Wpointer-compare %s
+// RUN: %clang_cc1 -fsyntax-only -verify -DSILENCE -Wall %s
+
+#ifdef SILENCE
+  // expected-no-diagnostics
+#endif
+
+int test1(int *a) {
+  return a == '\0';
+#ifndef SILENCE
+  // expected-warning@-2 {{comparison between NULL and null character}}
+#endif
+}
+
+int test2(int *a) {
+  return '\0' == a;
+#ifndef SILENCE
+  // expected-warning@-2 {{comparison between NULL and null character}}
+#endif
+}