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 NonnullStringConstantsChecker: 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
+  NonnullStringConstantsChecker.cpp
   NullabilityChecker.cpp
   NumberObjectConversionChecker.cpp
   ObjCAtSyncChecker.cpp
Index: lib/StaticAnalyzer/Checkers/NonnullStringConstantsChecker.cpp
===================================================================
--- /dev/null
+++ lib/StaticAnalyzer/Checkers/NonnullStringConstantsChecker.cpp
@@ -0,0 +1,141 @@
+//==-- RetainCountChecker.cpp - Checks for leaks and other issues -*- C++ -*--//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  Class definition for NonnullStringConstantsChecker.
+//  This checker adds an assumption that constant string-like globals are
+//  non-null, as otherwise they generally do not convey any useful information.
+//  The assumption is useful, as many framework use such global const strings,
+//  and the analyzer might not be able to infer the global value if the
+//  definition is in a separate translation unit.
+//  The following types (and their typedef aliases) are considered string-like:
+//   - `char* const`
+//   - `const CFStringRef` from CoreFoundation
+//   - `NSString* const` from Foundation
+//
+//  Checker uses are defined in the test file:
+//   - test/Analysis/nonnull-string-constants.mm
+//
+//===----------------------------------------------------------------------===//
+
+//
+// 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 NonnullStringConstantsChecker : public Checker<check::Location> {
+  mutable IdentifierInfo *NSStringII = nullptr;
+  mutable IdentifierInfo *CFStringRefII = nullptr;
+
+public:
+  NonnullStringConstantsChecker() {}
+
+  /// Add an assumption that const string-like globals are non-null.
+  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;
+
+  /// \param val loaded lvalue.
+  /// \return whether {@code val} is a string-like const global.
+  bool isGlobalConstString(SVal val) const;
+
+  /// \return whether {@code type} is a string-like type.
+  bool isStringlike(QualType type) const;
+};
+
+} // namespace
+
+void NonnullStringConstantsChecker::initIdentifierInfo(ASTContext &Ctx) const {
+  if (NSStringII)
+    return;
+
+  NSStringII = &Ctx.Idents.get("NSString");
+  CFStringRefII = &Ctx.Idents.get("CFStringRef");
+}
+
+void NonnullStringConstantsChecker::checkLocation(SVal location, bool isLoad,
+                                                 const Stmt *S,
+                                                 CheckerContext &C) const {
+  initIdentifierInfo(C.getASTContext());
+  if (!isLoad || !location.isValid())
+    return;
+
+  ProgramStateRef State = C.getState();
+  SVal 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 NonnullStringConstantsChecker::isGlobalConstString(SVal val) const {
+  Optional<loc::MemRegionVal> regionVal = val.getAs<loc::MemRegionVal>();
+  if (!regionVal)
+    return false;
+  auto *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 hasConst = type.isConstQualified();
+  if (isStringlike(type) && hasConst)
+    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.
+    hasConst = hasConst || type.isConstQualified();
+    if (isStringlike(type) && hasConst)
+      return true;
+  }
+  return false;
+}
+
+bool NonnullStringConstantsChecker::isStringlike(QualType type) const {
+
+  if (type->isPointerType() && type->getPointeeType()->isCharType())
+    return true;
+
+  if (const ObjCObjectPointerType *T = dyn_cast<ObjCObjectPointerType>(type)) {
+    return T->getInterfaceDecl()->getIdentifier() == NSStringII;
+  } else if (const TypedefType *T = dyn_cast<TypedefType>(type)) {
+    return T->getDecl()->getIdentifier() == CFStringRefII;
+  }
+  return false;
+}
+
+void ento::registerNonnullStringConstantsChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<NonnullStringConstantsChecker>();
+}
Index: test/Analysis/nonnull-string-constants.mm
===================================================================
--- /dev/null
+++ test/Analysis/nonnull-string-constants.mm
@@ -0,0 +1,91 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -verify %s
+
+// Nullability of const string-like globals.
+// Relies on the checker defined in
+// lib/StaticAnalyzer/Checkers/NonnullStringConstantsChecker.cpp.
+
+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}}
+}
+
+// char* const is also assumed to be non-null.
+extern const char *const ConstCharStarConst;
+void constCharStarCheckGlobal() {
+  clang_analyzer_eval(ConstCharStarConst); // expected-warning{{TRUE}}
+}
+
+// Pointer value can be mutable.
+extern char *const CharStarConst;
+void charStarCheckGlobal() {
+  clang_analyzer_eval(CharStarConst); // expected-warning{{TRUE}}
+}
+
+// But the pointer itself should be immutable.
+extern char *CharStar;
+void charStartCheckMutableGlobal() {
+  clang_analyzer_eval(CharStar); // expected-warning{{UNKNOWN}}
+}
+
+// Type definitions should also work across typedefs, for pointers:
+typedef char *const 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}}
+}
+
+// And for NSString *.
+typedef NSString *const nstr1;
+typedef nstr1 nstr2;
+extern nstr2 nglobalStr2;
+void testNestedTypedefsForNSString() {
+  clang_analyzer_eval(nglobalStr2); // expected-warning{{TRUE}}
+}