Index: clang-tidy/readability/CMakeLists.txt
===================================================================
--- clang-tidy/readability/CMakeLists.txt
+++ clang-tidy/readability/CMakeLists.txt
@@ -11,6 +11,7 @@
   IdentifierNamingCheck.cpp
   ImplicitBoolConversionCheck.cpp
   InconsistentDeclarationParameterNameCheck.cpp
+  MagicNumbersCheck.cpp
   MisleadingIndentationCheck.cpp
   MisplacedArrayIndexCheck.cpp
   NamedParameterCheck.cpp
Index: clang-tidy/readability/MagicNumbersCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/readability/MagicNumbersCheck.h
@@ -0,0 +1,62 @@
+//===--- MagicNumbersCheck.h - clang-tidy-----------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
+
+#include "../ClangTidy.h"
+
+#include <unordered_set>
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+/// Detects magic numbers, integer and floating point literals embedded in code.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/readability-magic-numbers.html
+class MagicNumbersCheck : public ClangTidyCheck {
+public:
+  MagicNumbersCheck(StringRef Name, ClangTidyContext *Context);
+  void storeOptions(ClangTidyOptions::OptionMap &Opts) override;
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  void checkIntegerMatch(const ast_matchers::MatchFinder::MatchResult &Result);
+  void checkFloatMatch(const ast_matchers::MatchFinder::MatchResult &Result);
+
+  bool isIgnoredIntegerValue(const llvm::APInt &IntValue) const;
+  bool isIgnoredFloatValue(const llvm::APFloat &FloatValue) const;
+
+  bool isConstantDefinition(const ast_type_traits::DynTypedNode &Parent) const;
+  bool
+  isConstantFieldDefinition(const ast_type_traits::DynTypedNode &Parent) const;
+  bool isTemplateArgumentAtSourceLocation(
+      const ast_type_traits::DynTypedNode &Parent) const;
+  bool isInitializerListForConstant(
+      const ast_matchers::MatchFinder::MatchResult &Result,
+      const ast_type_traits::DynTypedNode &Parent) const;
+  bool
+  isEnumerationDefinition(const ast_matchers::MatchFinder::MatchResult &Result,
+                          const ast_type_traits::DynTypedNode &Parent) const;
+
+  bool isConstant(const ast_matchers::MatchFinder::MatchResult &Result,
+                  const Expr &MatchResult) const;
+
+  const std::vector<std::string> IngnoredValuesInput;
+  std::vector<int64_t> IngnoredValues;
+};
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_MAGICNUMBERSCHECK_H
Index: clang-tidy/readability/MagicNumbersCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/readability/MagicNumbersCheck.cpp
@@ -0,0 +1,214 @@
+//===--- MagicNumbersCheck.cpp - clang-tidy-------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MagicNumbersCheck.h"
+#include "../utils/OptionsUtils.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+#include <algorithm>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace readability {
+
+const char DefaultIgnoredValues[] = "0;1;2;10;100;";
+
+MagicNumbersCheck::MagicNumbersCheck(StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      IngnoredValuesInput(utils::options::parseStringList(
+          Options.get("IgnoredValues", DefaultIgnoredValues))) {
+  IngnoredValues.reserve(IngnoredValuesInput.size());
+  for (const std::string &IgnoredValue : IngnoredValuesInput) {
+    IngnoredValues.push_back(std::stoll(IgnoredValue));
+  }
+  std::sort(IngnoredValues.begin(), IngnoredValues.end());
+}
+
+void MagicNumbersCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "IgnoredValues", DefaultIgnoredValues);
+}
+
+void MagicNumbersCheck::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(integerLiteral().bind("ii"), this);
+  Finder->addMatcher(floatLiteral().bind("ff"), this);
+}
+
+void MagicNumbersCheck::check(const MatchFinder::MatchResult &Result) {
+  checkIntegerMatch(Result);
+  checkFloatMatch(Result);
+}
+
+void MagicNumbersCheck::checkIntegerMatch(
+    const MatchFinder::MatchResult &Result) {
+  const IntegerLiteral *MatchedInteger =
+      Result.Nodes.getNodeAs<IntegerLiteral>("ii");
+  if (MatchedInteger) {
+
+    if (Result.SourceManager->isMacroBodyExpansion(
+            MatchedInteger->getLocation()))
+      return;
+
+    llvm::APInt Value = MatchedInteger->getValue();
+    if (isIgnoredIntegerValue(Value))
+      return;
+
+    if (isConstant(Result, *MatchedInteger))
+      return;
+
+    SmallVector<char, 32> Str(32, '\0');
+    Str.resize(0);
+
+    Value.toString(Str, 10, true);
+
+    diag(MatchedInteger->getLocation(), "magic number integer literal %0")
+        << Str.data();
+  }
+}
+
+void MagicNumbersCheck::checkFloatMatch(
+    const MatchFinder::MatchResult &Result) {
+
+  const FloatingLiteral *MatchedFloat =
+      Result.Nodes.getNodeAs<FloatingLiteral>("ff");
+  if (MatchedFloat) {
+
+    if (Result.SourceManager->isMacroBodyExpansion(MatchedFloat->getLocation()))
+      return;
+
+    llvm::APFloat Value = MatchedFloat->getValue();
+    if (isIgnoredFloatValue(Value))
+      return;
+
+    if (isConstant(Result, *MatchedFloat))
+      return;
+
+    SmallVector<char, 32> Str(32, '\0');
+    Str.resize(0);
+
+    Value.toString(Str, 10, true);
+
+    diag(MatchedFloat->getLocation(), "magic number float literal %0")
+        << Str.data();
+  }
+}
+
+bool MagicNumbersCheck::isIgnoredIntegerValue(
+    const llvm::APInt &IntValue) const {
+  int64_t Value = IntValue.getZExtValue();
+  return std::binary_search(IngnoredValues.begin(), IngnoredValues.end(),
+                            Value);
+}
+
+bool MagicNumbersCheck::isIgnoredFloatValue(
+    const llvm::APFloat &FloatValue) const {
+  return FloatValue.isZero();
+}
+
+bool MagicNumbersCheck::isConstantDefinition(
+    const ast_type_traits::DynTypedNode &Parent) const {
+  const VarDecl *AsVarDecl = Parent.get<VarDecl>();
+  if (AsVarDecl) {
+    if (AsVarDecl->getType().isConstQualified()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool MagicNumbersCheck::isConstantFieldDefinition(
+    const ast_type_traits::DynTypedNode &Parent) const {
+  const FieldDecl *AsFieldDecl = Parent.get<FieldDecl>();
+  if (AsFieldDecl) {
+    if (AsFieldDecl->getType().isConstQualified()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool MagicNumbersCheck::isTemplateArgumentAtSourceLocation(
+    const ast_type_traits::DynTypedNode &Parent) const {
+  const SubstNonTypeTemplateParmExpr *AsTemplateArgument =
+      Parent.get<SubstNonTypeTemplateParmExpr>();
+  if (AsTemplateArgument) {
+    return true;
+  }
+  return false;
+}
+
+bool MagicNumbersCheck::isInitializerListForConstant(
+    const MatchFinder::MatchResult &Result,
+    const ast_type_traits::DynTypedNode &Parent) const {
+  const InitListExpr *AsInitListExpr = Parent.get<InitListExpr>();
+  if (AsInitListExpr) {
+    for (const ast_type_traits::DynTypedNode &InitListParent :
+         Result.Context->getParents(*AsInitListExpr)) {
+      const VarDecl *AsVarDecl = InitListParent.get<VarDecl>();
+      if (AsVarDecl) {
+        if (AsVarDecl->getType().isConstQualified()) {
+          // good const definition
+          return true;
+        }
+      }
+
+      if (isInitializerListForConstant(Result, InitListParent))
+        return true;
+    }
+  }
+
+  return false;
+}
+
+bool MagicNumbersCheck::isEnumerationDefinition(
+    const MatchFinder::MatchResult &Result,
+    const ast_type_traits::DynTypedNode &Parent) const {
+  const EnumConstantDecl *AsEnumConstantDecl = Parent.get<EnumConstantDecl>();
+  if (AsEnumConstantDecl)
+    return true;
+
+  for (const ast_type_traits::DynTypedNode &GrandParent :
+       Result.Context->getParents(Parent)) {
+    if (isEnumerationDefinition(Result, GrandParent))
+      return true;
+  }
+
+  return false;
+}
+
+bool MagicNumbersCheck::isConstant(
+    const ast_matchers::MatchFinder::MatchResult &Result,
+    const Expr &MatchResult) const {
+  for (const ast_type_traits::DynTypedNode &Parent :
+       Result.Context->getParents(MatchResult)) {
+
+    if (isConstantDefinition(Parent))
+      return true;
+
+    if (isConstantFieldDefinition(Parent))
+      return true;
+
+    if (isTemplateArgumentAtSourceLocation(Parent))
+      return true;
+
+    if (isInitializerListForConstant(Result, Parent))
+      return true;
+
+    if (isEnumerationDefinition(Result, Parent))
+      return true;
+  }
+
+  return false;
+}
+
+} // namespace readability
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/readability/ReadabilityTidyModule.cpp
===================================================================
--- clang-tidy/readability/ReadabilityTidyModule.cpp
+++ clang-tidy/readability/ReadabilityTidyModule.cpp
@@ -20,6 +20,7 @@
 #include "IdentifierNamingCheck.h"
 #include "ImplicitBoolConversionCheck.h"
 #include "InconsistentDeclarationParameterNameCheck.h"
+#include "MagicNumbersCheck.h"
 #include "MisleadingIndentationCheck.h"
 #include "MisplacedArrayIndexCheck.h"
 #include "NamedParameterCheck.h"
@@ -65,6 +66,8 @@
         "readability-implicit-bool-conversion");
     CheckFactories.registerCheck<InconsistentDeclarationParameterNameCheck>(
         "readability-inconsistent-declaration-parameter-name");
+    CheckFactories.registerCheck<MagicNumbersCheck>(
+        "readability-magic-numbers");
     CheckFactories.registerCheck<MisleadingIndentationCheck>(
         "readability-misleading-indentation");
     CheckFactories.registerCheck<MisplacedArrayIndexCheck>(
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -154,6 +154,12 @@
   Warns or suggests alternatives if SIMD intrinsics are used which can be replaced by
   ``std::experimental::simd`` operations.
 
+- New :doc:`readability-magic-numbers
+  <http://clang.llvm.org/extra/clang-tidy/checks/readability-magic-numbers.html>` check.
+
+  Detects usage of magic numbers, numbers that are used as literals instead of
+  introduced via constants or symbols.
+
 - New :doc:`readability-simplify-subscript-expr
   <clang-tidy/checks/readability-simplify-subscript-expr>` check.
 
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -217,6 +217,7 @@
    readability-identifier-naming
    readability-implicit-bool-conversion
    readability-inconsistent-declaration-parameter-name
+   readability-magic-numbers
    readability-misleading-indentation
    readability-misplaced-array-index
    readability-named-parameter
Index: docs/clang-tidy/checks/readability-magic-numbers.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/readability-magic-numbers.rst
@@ -0,0 +1,19 @@
+.. title:: clang-tidy - readability-magic-numbers
+
+readability-magic-numbers
+==========================
+
+Detects magic numbers, integer or floating point literal that are embedded in
+code and not introduced via constants or symbols.
+
+Bad example:
+
+.. code-block:: c++
+
+   double circleArea = 3.1415926535 * radius * radius;
+
+Good example:
+
+.. code-block:: c++
+
+   double circleArea = M_PI * radius * radius;
Index: test/clang-tidy/readability-magic-numbers.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/readability-magic-numbers.cpp
@@ -0,0 +1,107 @@
+// RUN: %check_clang_tidy %s readability-magic-numbers %t
+
+template <typename T, int V>
+struct ValueBucket {
+  T value[V];
+};
+
+int BadGlobalInt = 5;
+// CHECK-MESSAGES: :[[@LINE-1]]:20: warning: magic number integer literal 5 [readability-magic-numbers]
+
+int IntSquarer(int param) {
+  return param * param;
+}
+
+void BuggyFunction() {
+  int BadLocalInt = 6;
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: magic number integer literal 6 [readability-magic-numbers]
+
+  (void)IntSquarer(7);
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: magic number integer literal 7 [readability-magic-numbers]
+
+  int LocalArray[8];
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: magic number integer literal 8 [readability-magic-numbers]
+
+  for (int ii = 0; ii < 8; ++ii)
+  // CHECK-MESSAGES: :[[@LINE-1]]:25: warning: magic number integer literal 8 [readability-magic-numbers]
+  {
+    LocalArray[ii] = 3 * ii;
+    // CHECK-MESSAGES: :[[@LINE-1]]:22: warning: magic number integer literal 3 [readability-magic-numbers]
+  }
+
+  ValueBucket<int, 4> Bucket;
+  // CHECK-MESSAGES: :[[@LINE-1]]:20: warning: magic number integer literal 4 [readability-magic-numbers]
+}
+
+class TwoIntContainer {
+public:
+  TwoIntContainer(int val) : anotherMember(val * val), yetAnotherMember(6), anotherConstant(val + val) {}
+  // CHECK-MESSAGES: :[[@LINE-1]]:73: warning: magic number integer literal 6 [readability-magic-numbers]
+
+  int getValue() const;
+
+private:
+  int oneMember = 9;
+  // CHECK-MESSAGES: :[[@LINE-1]]:19: warning: magic number integer literal 9 [readability-magic-numbers]
+
+  int anotherMember;
+
+  int yetAnotherMember;
+
+  const int oneConstant = 2;
+
+  const int anotherConstant;
+};
+
+int ValueArray[] = {3, 5};
+// CHECK-MESSAGES: :[[@LINE-1]]:21: warning: magic number integer literal 3 [readability-magic-numbers]
+// CHECK-MESSAGES: :[[@LINE-2]]:24: warning: magic number integer literal 5 [readability-magic-numbers]
+
+float FloatPiVariable = 3.1415926535f;
+// CHECK-MESSAGES: :[[@LINE-1]]:25: warning: magic number float literal 3.141592741 [readability-magic-numbers]
+double DoublePiVariable = 6.283185307;
+// CHECK-MESSAGES: :[[@LINE-1]]:27: warning: magic number float literal 6.283185307 [readability-magic-numbers]
+
+/*
+ * Clean code
+ */
+
+#define INT_MACRO 5
+
+const int GoodGlobalIntContant = 42;
+
+constexpr int AlsoGoodGlobalIntContant = 42;
+
+void SolidFunction() {
+  const int GoodLocalIntContant = 43;
+
+  (void)IntSquarer(GoodLocalIntContant);
+
+  int LocalArray[INT_MACRO];
+
+  ValueBucket<int, INT_MACRO> Bucket;
+}
+
+const int ConstValueArray[] = {7, 9};
+
+const int ConstValueArray2D[2][2] = {{7, 9}, {13, 15}};
+
+/*
+ * no warnings for grandfathered values
+ */
+int GrandfatheredValues[] = {0, 1, 2, 10, 100, -1, -10, -100};
+
+/*
+ * no warnings for enums
+ */
+enum Smorgasbord {
+  STARTER,
+  ALPHA = 3,
+  BETA = 1 << 5,
+};
+
+const float FloatPiConstant = 3.1415926535f;
+const double DoublePiConstant = 6.283185307;
+
+double DoubleZeroIsAccepted = 0.0;
+float FloatZeroIsAccepted = 0.0f;