Index: clang-tidy/readability/ContainerSizeEmptyCheck.cpp
===================================================================
--- clang-tidy/readability/ContainerSizeEmptyCheck.cpp
+++ clang-tidy/readability/ContainerSizeEmptyCheck.cpp
@@ -37,7 +37,7 @@
           namedDecl(
               has(cxxMethodDecl(
                       isConst(), parameterCountIs(0), isPublic(),
-                      hasName("size"),
+                      anyOf(hasName("size"), hasName("length")),
                       returns(qualType(isInteger(), unless(booleanType()))))
                       .bind("size")),
               has(cxxMethodDecl(isConst(), parameterCountIs(0), isPublic(),
@@ -62,7 +62,7 @@
       cxxMemberCallExpr(on(expr(anyOf(hasType(ValidContainer),
                                       hasType(pointsTo(ValidContainer)),
                                       hasType(references(ValidContainer))))),
-                        callee(cxxMethodDecl(hasName("size"))), WrongUse,
+                        callee(cxxMethodDecl(anyOf(hasName("size"), hasName("length")))), WrongUse,
                         unless(hasAncestor(cxxMethodDecl(
                             ofClass(equalsBoundNode("container"))))))
           .bind("SizeCallExpr"),
@@ -203,7 +203,8 @@
   if (MemberCall) {
     diag(MemberCall->getBeginLoc(),
          "the 'empty' method should be used to check "
-         "for emptiness instead of 'size'")
+         "for emptiness instead of '%0'")
+        << MemberCall->getMethodDecl()->getName()
         << Hint;
   } else {
     diag(BinCmp->getBeginLoc(),
Index: test/clang-tidy/readability-container-size-empty.cpp
===================================================================
--- test/clang-tidy/readability-container-size-empty.cpp
+++ test/clang-tidy/readability-container-size-empty.cpp
@@ -17,6 +17,7 @@
   bool operator!=(const char *) const;
   basic_string<T> operator+(const basic_string<T>& other) const;
   unsigned long size() const;
+  unsigned long length() const;
   bool empty() const;
 };
 
@@ -106,30 +107,42 @@
   std::string str2;
   std::wstring wstr;
   (void)(str.size() + 0);
+  (void)(str.length() + 0);
   (void)(str.size() - 0);
+  (void)(str.length() - 0);
   (void)(0 + str.size());
+  (void)(0 + str.length());
   (void)(0 - str.size());
+  (void)(0 - str.length());
   if (intSet.size() == 0)
     ;
   // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
   // CHECK-FIXES: {{^  }}if (intSet.empty()){{$}}
-  // CHECK-MESSAGES: :32:8: note: method 'set'::empty() defined here
+  // CHECK-MESSAGES: :33:8: note: method 'set'::empty() defined here
   if (intSet == std::set<int>())
     ;
   // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness
   // CHECK-FIXES: {{^  }}if (intSet.empty()){{$}}
-  // CHECK-MESSAGES: :32:8: note: method 'set'::empty() defined here
+  // CHECK-MESSAGES: :33:8: note: method 'set'::empty() defined here
   if (s_func() == "")
     ;
   // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
   // CHECK-FIXES: {{^  }}if (s_func().empty()){{$}}
   if (str.size() == 0)
     ;
-  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+  // CHECK-FIXES: {{^  }}if (str.empty()){{$}}
+  if (str.length() == 0)
+    ;
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'length' [readability-container-size-empty]
   // CHECK-FIXES: {{^  }}if (str.empty()){{$}}
   if ((str + str2).size() == 0)
     ;
-  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+  // CHECK-FIXES: {{^  }}if ((str + str2).empty()){{$}}
+  if ((str + str2).length() == 0)
+    ;
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'length' [readability-container-size-empty]
   // CHECK-FIXES: {{^  }}if ((str + str2).empty()){{$}}
   if (str == "")
     ;
@@ -141,7 +154,11 @@
   // CHECK-FIXES: {{^  }}if ((str + str2).empty()){{$}}
   if (wstr.size() == 0)
     ;
-  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
+  // CHECK-FIXES: {{^  }}if (wstr.empty()){{$}}
+  if (wstr.length() == 0)
+    ;
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'length' [readability-container-size-empty]
   // CHECK-FIXES: {{^  }}if (wstr.empty()){{$}}
   if (wstr == "")
     ;
@@ -150,7 +167,7 @@
   std::vector<int> vect;
   if (vect.size() == 0)
     ;
-  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used to check for emptiness instead of 'size' [readability-container-size-empty]
   // CHECK-FIXES: {{^  }}if (vect.empty()){{$}}
   if (vect == std::vector<int>())
     ;
@@ -423,17 +440,17 @@
   if (templated_container.size())
     ;
   // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
-  // CHECK-MESSAGES: :44:8: note: method 'TemplatedContainer'::empty() defined here
+  // CHECK-MESSAGES: :45:8: note: method 'TemplatedContainer'::empty() defined here
   // CHECK-FIXES: {{^  }}if (!templated_container.empty()){{$}}
   if (templated_container != TemplatedContainer<T>())
     ;
   // CHECK-MESSAGES: :[[@LINE-2]]:7: warning: the 'empty' method should be used
-  // CHECK-MESSAGES: :44:8: note: method 'TemplatedContainer'::empty() defined here
+  // CHECK-MESSAGES: :45:8: note: method 'TemplatedContainer'::empty() defined here
   // CHECK-FIXES: {{^  }}if (!templated_container.empty()){{$}}
   // CHECK-FIXES-NEXT: ;
   CHECKSIZE(templated_container);
   // CHECK-MESSAGES: :[[@LINE-1]]:13: warning: the 'empty' method should be used
-  // CHECK-MESSAGES: :44:8: note: method 'TemplatedContainer'::empty() defined here
+  // CHECK-MESSAGES: :45:8: note: method 'TemplatedContainer'::empty() defined here
   // CHECK-FIXES: CHECKSIZE(templated_container);
 }