Index: include/clang/StaticAnalyzer/Checkers/Checkers.td
===================================================================
--- include/clang/StaticAnalyzer/Checkers/Checkers.td
+++ include/clang/StaticAnalyzer/Checkers/Checkers.td
@@ -132,6 +132,10 @@
   HelpText<"Generate dynamic type information">,
   DescFile<"DynamicTypePropagation.cpp">;
 
+def NonnilStringConstantsChecker: Checker<"NonnilStringConstants">,
+  HelpText<"Assume that const string-like globals are non-null">,
+  DescFile<"NonilStringConstantsChecker.cpp">;
+
 } // end "core"
 
 let ParentPackage = CoreAlpha in {
Index: lib/StaticAnalyzer/Checkers/CMakeLists.txt
===================================================================
--- lib/StaticAnalyzer/Checkers/CMakeLists.txt
+++ lib/StaticAnalyzer/Checkers/CMakeLists.txt
@@ -57,6 +57,7 @@
   NSErrorChecker.cpp
   NoReturnFunctionChecker.cpp
   NonNullParamChecker.cpp
+  NonnilStringConstantsChecker.cpp
   NullabilityChecker.cpp
   NumberObjectConversionChecker.cpp
   ObjCAtSyncChecker.cpp
Index: lib/StaticAnalyzer/Checkers/NonnilStringConstantsChecker.cpp
===================================================================
--- /dev/null
+++ lib/StaticAnalyzer/Checkers/NonnilStringConstantsChecker.cpp
@@ -0,0 +1,121 @@
+
+//
+// This checker ensures that const string globals are assumed to be non-null.
+//
+#include "ClangSACheckers.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "clang/StaticAnalyzer/Core/CheckerManager.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
+#include "clang/StaticAnalyzer/Core/PathSensitive/ExprEngine.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+
+class NonnilStringConstantsChecker : public Checker<check::Location> {
+  mutable IdentifierInfo *NSStringII = nullptr;
+  mutable IdentifierInfo *CFStringRefII = nullptr;
+
+public:
+  NonnilStringConstantsChecker(AnalyzerOptions &AO) {}
+
+  void checkLocation(SVal l, bool isLoad, const Stmt *S,
+                     CheckerContext &C) const;
+
+private:
+  /// Lazily initialize cache for required identifier informations.
+  void initIdentifierInfo(ASTContext &Ctx) const;
+  bool typeIsConstString(QualType type, bool isConstQualified) const;
+  bool isGlobalConstString(SVal val) const;
+};
+
+} // namespace
+
+void NonnilStringConstantsChecker::initIdentifierInfo(ASTContext &Ctx) const {
+  if (NSStringII)
+    return;
+
+  NSStringII = &Ctx.Idents.get("NSString");
+  CFStringRefII = &Ctx.Idents.get("CFStringRef");
+}
+
+void NonnilStringConstantsChecker::checkLocation(SVal location, bool isLoad,
+                                                 const Stmt *S,
+                                                 CheckerContext &C) const {
+  initIdentifierInfo(C.getASTContext());
+  if (!isLoad)
+    return;
+
+  ProgramStateRef State = C.getState();
+  SVal V = UnknownVal();
+  if (location.isValid()) {
+    V = State->getSVal(location.castAs<Loc>());
+  }
+
+  if (isGlobalConstString(location)) {
+    Optional<DefinedOrUnknownSVal> Constr = V.getAs<DefinedOrUnknownSVal>();
+
+    if (Constr) {
+
+      // Assume that the variable is non-null.
+      ProgramStateRef OutputState = State->assume(*Constr, true);
+      C.addTransition(OutputState);
+    }
+  }
+}
+
+
+bool NonnilStringConstantsChecker::isGlobalConstString(SVal val) const {
+  Optional<loc::MemRegionVal> regionVal = val.getAs<loc::MemRegionVal>();
+  if (!regionVal)
+    return false;
+  const VarRegion *region = dyn_cast<VarRegion>(regionVal->getAsRegion());
+  if (!region)
+    return false;
+  const VarDecl *decl = region->getDecl();
+
+  if (!decl->hasGlobalStorage())
+    return false;
+
+  QualType type = decl->getType();
+  bool hasOuterConst = type.isConstQualified();
+  if (typeIsConstString(type, hasOuterConst))
+    return true;
+
+  // Look through the typedefs.
+  while (const TypedefType *T = dyn_cast<TypedefType>(type)) {
+    type = T->getDecl()->getUnderlyingType();
+
+    // It is sufficient for any intermediate typedef
+    // to be classified const.
+    hasOuterConst |= type.isConstQualified();
+    if (typeIsConstString(type, hasOuterConst))
+      return true;
+  }
+  return false;
+}
+
+bool NonnilStringConstantsChecker::typeIsConstString(
+    QualType type, bool isConstQualified) const {
+
+  // Match `const char*`.
+  if (type->isPointerType() && type->getPointeeType()->isCharType() &&
+      type->getPointeeType().isConstQualified())
+    return true;
+
+  IdentifierInfo *II;
+  if (const ObjCObjectPointerType *T = dyn_cast<ObjCObjectPointerType>(type)) {
+    II = T->getInterfaceDecl()->getIdentifier();
+  } else if (const TypedefType *T = dyn_cast<TypedefType>(type)) {
+    II = T->getDecl()->getIdentifier();
+  }
+
+  // Match `NSString* const` or `const CFStringRef`.
+  return isConstQualified && (II == NSStringII || II == CFStringRefII);
+}
+
+void ento::registerNonnilStringConstantsChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<NonnilStringConstantsChecker>(Mgr.getAnalyzerOptions());
+}
Index: test/Analysis/nonnil-string-constants.mm
===================================================================
--- /dev/null
+++ test/Analysis/nonnil-string-constants.mm
@@ -0,0 +1,80 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -verify %s
+
+// Nullability of const string-like globals.
+void clang_analyzer_eval(bool);
+
+@class NSString;
+typedef const struct __CFString *CFStringRef;
+
+// Global NSString* is non-null.
+extern NSString *const StringConstGlobal;
+void stringConstGlobal() {
+  clang_analyzer_eval(StringConstGlobal); // expected-warning{{TRUE}}
+}
+
+// The logic does not apply to local variables though.
+extern NSString *stringGetter();
+void stringConstLocal() {
+  NSString *const local = stringGetter();
+  clang_analyzer_eval(local); // expected-warning{{UNKNOWN}}
+}
+
+// Global const CFStringRef's are also assumed to be non-null.
+extern const CFStringRef CFStringConstGlobal;
+void cfStringCheckGlobal() {
+  clang_analyzer_eval(CFStringConstGlobal); // expected-warning{{TRUE}}
+}
+
+// But only "const" ones.
+extern CFStringRef CFStringNonConstGlobal;
+void cfStringCheckMutableGlobal() {
+  clang_analyzer_eval(CFStringNonConstGlobal); // expected-warning{{UNKNOWN}}
+}
+
+// Const char* is also assumed to be non-null.
+extern const char *const ConstCharStarConst;
+void constCharStarCheckGlobal() {
+  clang_analyzer_eval(ConstCharStarConst); // expected-warning{{TRUE}}
+}
+
+// For char* we do not require a pointer itself to be immutable.
+extern const char *CharStarConst;
+void charStarCheckGlobal() {
+  clang_analyzer_eval(CharStarConst); // expected-warning{{TRUE}}
+}
+
+// But the pointed data should be.
+extern char *CharStar;
+void charStartCheckMutableGlobal() {
+  clang_analyzer_eval(CharStar); // expected-warning{{UNKNOWN}}
+}
+
+// Type definitions should also work across typedefs, for pointers:
+typedef const char *str;
+extern str globalStr;
+void charStarCheckTypedef() {
+  clang_analyzer_eval(globalStr); // expected-warning{{TRUE}}
+}
+
+// And for types.
+typedef NSString *const NStr;
+extern NStr globalNSString;
+void NSStringCheckTypedef() {
+  clang_analyzer_eval(globalNSString); // expected-warning{{TRUE}}
+}
+
+// Note that constness could be either inside
+// the var declaration, or in a typedef.
+typedef NSString *NStr2;
+extern const NStr2 globalNSString2;
+void NSStringCheckConstTypedef() {
+  clang_analyzer_eval(globalNSString2); // expected-warning{{TRUE}}
+}
+
+// Nested typedefs should work as well.
+typedef const CFStringRef str1;
+typedef str1 str2;
+extern str2 globalStr2;
+void testNestedTypedefs() {
+  clang_analyzer_eval(globalStr2); // expected-warning{{TRUE}}
+}