Index: clang-tidy/bugprone/SizeofExpressionCheck.cpp
===================================================================
--- clang-tidy/bugprone/SizeofExpressionCheck.cpp
+++ clang-tidy/bugprone/SizeofExpressionCheck.cpp
@@ -84,8 +84,11 @@
   const auto IntegerCallExpr = expr(ignoringParenImpCasts(
       callExpr(anyOf(hasType(isInteger()), hasType(enumType())),
                unless(isInTemplateInstantiation()))));
-  const auto SizeOfExpr =
-      expr(anyOf(sizeOfExpr(has(type())), sizeOfExpr(has(expr()))));
+  const auto SizeOfExpr = expr(anyOf(
+      sizeOfExpr(
+          has(hasUnqualifiedDesugaredType(type().bind("sizeof-arg-type")))),
+      sizeOfExpr(has(expr(hasType(
+          hasUnqualifiedDesugaredType(type().bind("sizeof-arg-type"))))))));
   const auto SizeOfZero = expr(
       sizeOfExpr(has(ignoringParenImpCasts(expr(integerLiteral(equals(0)))))));
 
@@ -209,6 +212,36 @@
                hasSizeOfDescendant(8, expr(SizeOfExpr, unless(SizeOfZero))))))))
           .bind("sizeof-sizeof-expr"),
       this);
+
+  // Detect sizeof in pointer aritmetic like: N * sizeof(S) == P1 - P2 or
+  // (P1 - P2) / sizeof(S) where P1 and P2 are pointers to type S.
+  const auto PtrDiffExpr = binaryOperator(
+      hasOperatorName("-"),
+      hasLHS(expr(hasType(hasUnqualifiedDesugaredType(pointerType(pointee(
+          hasUnqualifiedDesugaredType(type().bind("left-ptr-type")))))))),
+      hasRHS(expr(hasType(hasUnqualifiedDesugaredType(pointerType(pointee(
+          hasUnqualifiedDesugaredType(type().bind("right-ptr-type")))))))));
+
+  Finder->addMatcher(
+      binaryOperator(
+          anyOf(hasOperatorName("=="), hasOperatorName("!="),
+                hasOperatorName("<"), hasOperatorName("<="),
+                hasOperatorName(">"), hasOperatorName(">="),
+                hasOperatorName("+"), hasOperatorName("-")),
+          hasEitherOperand(expr(anyOf(
+              ignoringParenImpCasts(SizeOfExpr),
+              ignoringParenImpCasts(binaryOperator(
+                  hasOperatorName("*"),
+                  hasEitherOperand(ignoringParenImpCasts(SizeOfExpr))))))),
+          hasEitherOperand(ignoringParenImpCasts(PtrDiffExpr)))
+          .bind("sizeof-in-ptr-arithmetic-mul"),
+      this);
+
+  Finder->addMatcher(binaryOperator(hasOperatorName("/"),
+                                    hasLHS(ignoringParenImpCasts(PtrDiffExpr)),
+                                    hasRHS(ignoringParenImpCasts(SizeOfExpr)))
+                         .bind("sizeof-in-ptr-arithmetic-div"),
+                     this);
 }
 
 void SizeofExpressionCheck::check(const MatchFinder::MatchResult &Result) {
@@ -275,6 +308,26 @@
   } else if (const auto *E =
                  Result.Nodes.getNodeAs<Expr>("sizeof-multiply-sizeof")) {
     diag(E->getBeginLoc(), "suspicious 'sizeof' by 'sizeof' multiplication");
+  } else if (const auto *E =
+                 Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-mul")) {
+    const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type");
+    const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type");
+    const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
+
+    if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) {
+      diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in "
+                              "pointer arithmetic");
+    }
+  } else if (const auto *E =
+                 Result.Nodes.getNodeAs<Expr>("sizeof-in-ptr-arithmetic-div")) {
+    const auto *LPtrTy = Result.Nodes.getNodeAs<Type>("left-ptr-type");
+    const auto *RPtrTy = Result.Nodes.getNodeAs<Type>("right-ptr-type");
+    const auto *SizeofArgTy = Result.Nodes.getNodeAs<Type>("sizeof-arg-type");
+
+    if ((LPtrTy == RPtrTy) && (LPtrTy == SizeofArgTy)) {
+      diag(E->getBeginLoc(), "suspicious usage of 'sizeof(...)' in "
+                              "pointer arithmetic");
+    }
   }
 }
 
Index: test/clang-tidy/bugprone-sizeof-expression.cpp
===================================================================
--- test/clang-tidy/bugprone-sizeof-expression.cpp
+++ test/clang-tidy/bugprone-sizeof-expression.cpp
@@ -231,6 +231,35 @@
   return sum;
 }
 
+int Test6() {
+  int sum = 0;
+
+  struct S A = AsStruct(), B = AsStruct();
+  struct S *P = &A, *Q = &B;
+  sum += sizeof(struct S) == P - Q;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += 5 * sizeof(S) != P - Q;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += sizeof(S) < P - Q;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += 5 * sizeof(S) <= P - Q;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += 5 * sizeof(*P) >= P - Q;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += Q - P > 3 * sizeof(*P);
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += sizeof(S) + (P - Q);
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += 5 * sizeof(S) - (P - Q);
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += (P - Q) / sizeof(S);
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+  sum += (P - Q) / sizeof(*Q);
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: suspicious usage of 'sizeof(...)' in pointer arithmetic
+
+  return sum;
+}
+
 int ValidExpressions() {
   int A[] = {1, 2, 3, 4};
   static const char str[] = "hello";