Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -142,6 +142,7 @@
 def : DiagGroup<"discard-qual">;
 def DivZero : DiagGroup<"division-by-zero">;
 def : DiagGroup<"div-by-zero", [DivZero]>;
+def DivSizeofPtr : DiagGroup<"sizeof-pointer-div">;
 
 def DocumentationHTML : DiagGroup<"documentation-html">;
 def DocumentationUnknownCommand : DiagGroup<"documentation-unknown-command">;
@@ -785,6 +786,7 @@
     SelfMove,
     SizeofArrayArgument,
     SizeofArrayDecay,
+    DivSizeofPtr,
     StringPlusInt,
     Trigraphs,
     Uninitialized,
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -3291,6 +3291,10 @@
   InGroup<TautologicalUndefinedCompare>;
 def note_reference_is_return_value : Note<"%0 returns a reference">;
 
+def warn_division_sizeof_ptr : Warning<
+  "division produces the incorrect number of array elements">,
+  InGroup<DivSizeofPtr>;
+
 def note_function_warning_silence : Note<
     "prefix with the address-of operator to silence this warning">;
 def note_function_to_function_call : Note<
Index: lib/Sema/SemaExpr.cpp
===================================================================
--- lib/Sema/SemaExpr.cpp
+++ lib/Sema/SemaExpr.cpp
@@ -5862,6 +5862,8 @@
       LangAS DestAS = DestTy->getPointeeType().getAddressSpace();
       if (SrcAS != DestAS)
         return CK_AddressSpaceConversion;
+      if (Context.hasCvrSimilarType(SrcTy, DestTy))
+        return CK_NoOp;
       return CK_BitCast;
     }
     case Type::STK_BlockPointer:
@@ -7762,7 +7764,12 @@
     if (isa<PointerType>(RHSType)) {
       LangAS AddrSpaceL = LHSPointer->getPointeeType().getAddressSpace();
       LangAS AddrSpaceR = RHSType->getPointeeType().getAddressSpace();
-      Kind = AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
+      if (AddrSpaceL != AddrSpaceR)
+        Kind = CK_AddressSpaceConversion;
+      else if (Context.hasCvrSimilarType(RHSType, LHSType))
+        Kind = CK_NoOp;
+      else
+        Kind = CK_BitCast;
       return checkPointerTypesForAssignment(*this, LHSType, RHSType);
     }
 
@@ -8670,6 +8677,39 @@
       << LHS.get()->getSourceRange() << RHS.get()->getSourceRange();
 }
 
+static void DiagnoseDivisionSizeofPointer(Sema &S, Expr *LHS, Expr *RHS,
+                                          SourceLocation Loc) {
+  UnaryExprOrTypeTraitExpr *LUE =
+      dyn_cast_or_null<UnaryExprOrTypeTraitExpr>(LHS);
+  UnaryExprOrTypeTraitExpr *RUE =
+      dyn_cast_or_null<UnaryExprOrTypeTraitExpr>(RHS);
+
+  if (!LUE || !RUE)
+    return;
+  if (LUE->getKind() != UETT_SizeOf || LUE->isArgumentType() ||
+      RUE->getKind() != UETT_SizeOf)
+    return;
+
+  QualType LHSTy;
+  QualType RHSTy;
+  LHS = LUE->getArgumentExpr()->IgnoreParens();
+  LHSTy = LHS->getType();
+
+  if (RUE->isArgumentType()) {
+    RHSTy = RUE->getArgumentType();
+  } else {
+    RHS = RUE->getArgumentExpr()->IgnoreParens();
+    RHSTy = RHS->getType();
+  }
+
+  if (!LHSTy->isPointerType() || RHSTy->isPointerType())
+    return;
+  if (LHSTy->getPointeeType() != RHSTy)
+    return;
+
+  S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS->getSourceRange();
+}
+
 static void DiagnoseBadDivideOrRemainderValues(Sema& S, ExprResult &LHS,
                                                ExprResult &RHS,
                                                SourceLocation Loc, bool IsDiv) {
@@ -8700,8 +8740,10 @@
 
   if (compType.isNull() || !compType->isArithmeticType())
     return InvalidOperands(Loc, LHS, RHS);
-  if (IsDiv)
+  if (IsDiv) {
     DiagnoseBadDivideOrRemainderValues(*this, LHS, RHS, Loc, IsDiv);
+    DiagnoseDivisionSizeofPointer(*this, LHS.get(), RHS.get(), Loc);
+  }
   return compType;
 }
 
@@ -13428,6 +13470,7 @@
   PopExpressionEvaluationContext();
 
   BlockScopeInfo *BSI = cast<BlockScopeInfo>(FunctionScopes.back());
+  BlockDecl *BD = BSI->TheDecl;
 
   if (BSI->HasImplicitReturnType)
     deduceClosureReturnType(*BSI);
@@ -13438,7 +13481,7 @@
   if (!BSI->ReturnType.isNull())
     RetTy = BSI->ReturnType;
 
-  bool NoReturn = BSI->TheDecl->hasAttr<NoReturnAttr>();
+  bool NoReturn = BD->hasAttr<NoReturnAttr>();
   QualType BlockTy;
 
   // Set the captured variables on the block.
@@ -13451,7 +13494,7 @@
                               Cap.isNested(), Cap.getInitExpr());
     Captures.push_back(NewCap);
   }
-  BSI->TheDecl->setCaptures(Context, Captures, BSI->CXXThisCaptureIndex != 0);
+  BD->setCaptures(Context, Captures, BSI->CXXThisCaptureIndex != 0);
 
   // If the user wrote a function type in some form, try to use that.
   if (!BSI->FunctionType.isNull()) {
@@ -13488,7 +13531,7 @@
     BlockTy = Context.getFunctionType(RetTy, None, EPI);
   }
 
-  DiagnoseUnusedParameters(BSI->TheDecl->parameters());
+  DiagnoseUnusedParameters(BD->parameters());
   BlockTy = Context.getBlockPointerType(BlockTy);
 
   // If needed, diagnose invalid gotos and switches in the block.
@@ -13496,19 +13539,19 @@
       !PP.isCodeCompletionEnabled())
     DiagnoseInvalidJumps(cast<CompoundStmt>(Body));
 
-  BSI->TheDecl->setBody(cast<CompoundStmt>(Body));
+  BD->setBody(cast<CompoundStmt>(Body));
 
   if (Body && getCurFunction()->HasPotentialAvailabilityViolations)
-    DiagnoseUnguardedAvailabilityViolations(BSI->TheDecl);
+    DiagnoseUnguardedAvailabilityViolations(BD);
 
   // Try to apply the named return value optimization. We have to check again
   // if we can do this, though, because blocks keep return statements around
   // to deduce an implicit return type.
   if (getLangOpts().CPlusPlus && RetTy->isRecordType() &&
-      !BSI->TheDecl->isDependentContext())
+      !BD->isDependentContext())
     computeNRVO(Body, BSI);
 
-  BlockExpr *Result = new (Context) BlockExpr(BSI->TheDecl, BlockTy);
+  BlockExpr *Result = new (Context) BlockExpr(BD, BlockTy);
   AnalysisBasedWarnings::Policy WP = AnalysisWarnings.getDefaultPolicy();
   PopFunctionScopeInfo(&WP, Result->getBlockDecl(), Result);
 
@@ -13531,7 +13574,7 @@
   }
 
   if (getCurFunction())
-    getCurFunction()->addBlock(BSI->TheDecl);
+    getCurFunction()->addBlock(BD);
 
   return Result;
 }
@@ -16533,4 +16576,4 @@
 
   return new (Context)
       ObjCAvailabilityCheckExpr(Version, AtLoc, RParen, Context.BoolTy);
-}
+}
\ No newline at end of file
Index: test/Sema/div-sizeof-ptr.c
===================================================================
--- test/Sema/div-sizeof-ptr.c
+++ test/Sema/div-sizeof-ptr.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -verify -Wsizeof-pointer-div -fsyntax-only
+
+void test(int *p, int **q) {
+    int a = sizeof(p) / sizeof(*p);      // expected-warning {{division produces the incorrect number of array elements}}
+    int b = sizeof p / sizeof *p;        // expected-warning {{division produces the incorrect number of array elements}}
+    int c = sizeof(*q) / sizeof(**q);    // expected-warning {{division produces the incorrect number of array elements}}
+    int d = sizeof(p) / sizeof(int);     // expected-warning {{division produces the incorrect number of array elements}}
+    
+    int e = sizeof(int *) / sizeof(int);
+    int f = sizeof(p) / sizeof(p);
+    int g = sizeof(*q) / sizeof(q);
+}