Index: clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tidy/misc/CMakeLists.txt
+++ clang-tidy/misc/CMakeLists.txt
@@ -7,6 +7,7 @@
   NewDeleteOverloadsCheck.cpp
   NonCopyableObjects.cpp
   NonPrivateMemberVariablesInClassesCheck.cpp
+  PlacementNewTargetSizeCheck.cpp
   RedundantExpressionCheck.cpp
   StaticAssertCheck.cpp
   ThrowByValueCatchByReferenceCheck.cpp
Index: clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tidy/misc/MiscTidyModule.cpp
@@ -14,6 +14,7 @@
 #include "NewDeleteOverloadsCheck.h"
 #include "NonCopyableObjects.h"
 #include "NonPrivateMemberVariablesInClassesCheck.h"
+#include "PlacementNewTargetSizeCheck.h"
 #include "RedundantExpressionCheck.h"
 #include "StaticAssertCheck.h"
 #include "ThrowByValueCatchByReferenceCheck.h"
@@ -39,6 +40,8 @@
         "misc-non-copyable-objects");
     CheckFactories.registerCheck<NonPrivateMemberVariablesInClassesCheck>(
         "misc-non-private-member-variables-in-classes");
+    CheckFactories.registerCheck<PlacementNewTargetSizeCheck>(
+        "misc-placement-new-target-size");
     CheckFactories.registerCheck<RedundantExpressionCheck>(
         "misc-redundant-expression");
     CheckFactories.registerCheck<StaticAssertCheck>("misc-static-assert");
Index: clang-tidy/misc/PlacementNewTargetSizeCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/misc/PlacementNewTargetSizeCheck.h
@@ -0,0 +1,36 @@
+//===--- PlacementNewTargetSizeCheck.h - clang-tidy -------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_PLACEMENTNEWTARGETSIZECHECK_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_PLACEMENTNEWTARGETSIZECHECK_H
+
+#include "../ClangTidyCheck.h"
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+/// This checker finds placement new statements that construct objects into allocated
+/// space where the pointer to that allocated space is of a type smaller than the
+/// constructed object and the pointer is implicitly cast to void *.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/misc-placement-new-target-size.html
+class PlacementNewTargetSizeCheck : public ClangTidyCheck {
+public:
+  PlacementNewTargetSizeCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_PLACEMENTNEWTARGETSIZECHECK_H
Index: clang-tidy/misc/PlacementNewTargetSizeCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/misc/PlacementNewTargetSizeCheck.cpp
@@ -0,0 +1,78 @@
+//===--- PlacementNewTargetSizeCheck.cpp - clang-tidy ---------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <iostream>
+
+#include "PlacementNewTargetSizeCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+namespace {
+CharUnits getSizeOfType(clang::ASTContext *const Context, const QualType& type) {
+  CharUnits TypeSize;
+  if (type->isRecordType()) {
+    const auto *CXXRecordDecl = type->getAsRecordDecl();
+    assert(CXXRecordDecl && "type->getAsRecordDecl() failed");
+    const auto &CXXDeclLayout =
+        CXXRecordDecl->getASTContext().getASTRecordLayout(CXXRecordDecl);
+    TypeSize = CXXDeclLayout.getDataSize();
+  } else if (type->isBuiltinType()) {
+    TypeSize = Context->getTypeSizeInChars(type);
+  } else {
+    // TODO: handle constructing into C-style array
+  }
+  return TypeSize;
+}
+}  // namespace
+
+void PlacementNewTargetSizeCheck::registerMatchers(MatchFinder *Finder) {
+  // We only want the records that call 'new' with a pointer that is implicitly cast into void *.
+  Finder->addMatcher(cxxNewExpr(hasDescendant(implicitCastExpr().bind("Cast"))).bind("Alloc"), this);
+}
+
+void PlacementNewTargetSizeCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const CXXNewExpr *Alloc = Result.Nodes.getNodeAs<CXXNewExpr>("Alloc");
+  assert(Alloc && "Matched node bound by 'Alloc' shoud be a 'CXXNewExpr'");
+
+  auto numPlacementArgs = Alloc->getNumPlacementArgs();
+  if (0 == numPlacementArgs) {
+    return;
+  }
+
+  auto type = Alloc->getAllocatedType();
+  CharUnits TypeSize = getSizeOfType(Result.Context, type);
+  if (TypeSize.isZero()) {
+    return;
+  }
+
+  // get ptr type of implicit cast
+  const ImplicitCastExpr *Cast = Result.Nodes.getNodeAs<ImplicitCastExpr>("Cast");
+  auto CastType = Cast->getSubExpr()->getType();
+  if (CastType->isPointerType()) {
+   CharUnits CastSize = getSizeOfType(Result.Context, CastType->getPointeeType());
+    if ((TypeSize - CastSize).isPositive()) {
+      diag(Alloc->getExprLoc(), "placement new has insufficient target size");
+    }
+  } else {
+    CastType->dump();
+    // TODO: handle constructing into C-style array
+  }
+
+}
+
+} // namespace misc
+} // namespace tidy
+} // namespace clang
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -130,6 +130,9 @@
   <clang-tidy/checks/modernize-use-override>` now supports `OverrideSpelling`
   and `FinalSpelling` options.
 
+- New :doc:`misc-placement-new-target-size
+  <clang-tidy/checks/misc-placement-new-target-size>` check.
+
 - New :doc:`openmp-exception-escape
   <clang-tidy/checks/openmp-exception-escape>` check.
 
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -184,6 +184,7 @@
    misc-new-delete-overloads
    misc-non-copyable-objects
    misc-non-private-member-variables-in-classes
+   misc-placement-new-target-size
    misc-redundant-expression
    misc-static-assert
    misc-throw-by-value-catch-by-reference
Index: docs/clang-tidy/checks/misc-placement-new-target-size.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/misc-placement-new-target-size.rst
@@ -0,0 +1,10 @@
+.. title:: clang-tidy - misc-placement-new-target-size
+
+misc-placement-new-target-size
+==============================
+
+
+Finds placement-new calls where the size of the pointee type of the placement 
+parameter is smaller than the size of the constructed type and the pointer is
+implicitly cast to ``void *``.
+
Index: test/clang-tidy/misc-placement-new-target-size.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/misc-placement-new-target-size.cpp
@@ -0,0 +1,14 @@
+// RUN: %check_clang_tidy %s misc-placement-new-target-size %t
+
+void f() {
+  struct Dummy {
+    int a;
+    int b;
+  };
+  int * ptr = new int;
+  new (ptr) Dummy;
+  delete ptr;
+
+}
+// CHECK-MESSAGES: :[[@LINE-1]]:6: warning: function 'f' is insufficiently awesome [misc-placement-new-target-size]
+