Index: clang-tidy/misc/CMakeLists.txt
===================================================================
--- clang-tidy/misc/CMakeLists.txt
+++ clang-tidy/misc/CMakeLists.txt
@@ -3,6 +3,7 @@
 add_clang_library(clangTidyMiscModule
   ArgumentCommentCheck.cpp
   BoolPointerImplicitConversion.cpp
+  ImplicitArgumentConversion.cpp
   MiscTidyModule.cpp
   RedundantSmartptrGet.cpp
   UseOverride.cpp
Index: clang-tidy/misc/ImplicitArgumentConversion.h
===================================================================
--- /dev/null
+++ clang-tidy/misc/ImplicitArgumentConversion.h
@@ -0,0 +1,29 @@
+//===--- ImplicitArgumentConversion.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_MISC_IMPLICIT_ARGUMENT_CONVERSION_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_IMPLICIT_ARGUMENT_CONVERSION_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+
+/// \brief 
+class ImplicitArgumentConversion : public ClangTidyCheck {
+public:
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+};
+
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MISC_IMPLICIT_ARGUMENT_CONVERSION_H
+
Index: clang-tidy/misc/ImplicitArgumentConversion.cpp
===================================================================
--- /dev/null
+++ clang-tidy/misc/ImplicitArgumentConversion.cpp
@@ -0,0 +1,59 @@
+//===--- ImplicitArgumentConversion.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 "ImplicitArgumentConversion.h"
+#include "clang/AST/TypeOrdering.h"
+#include <set>
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+void ImplicitArgumentConversion::registerMatchers(MatchFinder *Finder) {
+  Finder->addMatcher(callExpr().bind("call"), this);
+}
+
+void ImplicitArgumentConversion::check(const MatchFinder::MatchResult &Result) {
+  auto *Call = Result.Nodes.getStmtAs<CallExpr>("call");
+
+  // Get a set of types of literals that are on the call and a set of the
+  // corresponding types in the declaration. We only record them if it's coming
+  // from an implicit conversion of a literal.
+  std::set<QualType, QualTypeOrdering> DeclTypes;
+  std::set<QualType, QualTypeOrdering> CallTypes;
+  unsigned NumConversions = 0;
+  for (auto *Parm : Call->arguments()) {
+    // We only care about literals.
+    const Expr *PP = Parm->IgnoreImpCasts();
+    if (!isa<CharacterLiteral>(PP) && !isa<CXXBoolLiteralExpr>(PP) &&
+        !isa<FloatingLiteral>(PP) && !isa<IntegerLiteral>(PP))
+      continue;
+
+    DeclTypes.insert(Parm->getType());
+
+    // If we have an implicit conversion remember it.
+    if (auto *Cast = dyn_cast<ImplicitCastExpr>(Parm)) {
+      if (CallTypes.insert(Cast->getSubExpr()->getType()).second)
+        ++NumConversions;
+    } else {
+      CallTypes.insert(Parm->getType());
+    }
+  }
+
+  // We emit a warning if there are two or more implicit conversions. This is
+  // most likely a swap.
+  if (NumConversions >= 2 && DeclTypes == CallTypes) {
+    diag(Call->getLocStart(),
+         "multiple implicit literal conversions, possibly swapped arguments");
+  }
+}
+
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/misc/MiscTidyModule.cpp
===================================================================
--- clang-tidy/misc/MiscTidyModule.cpp
+++ clang-tidy/misc/MiscTidyModule.cpp
@@ -12,6 +12,7 @@
 #include "../ClangTidyModuleRegistry.h"
 #include "ArgumentCommentCheck.h"
 #include "BoolPointerImplicitConversion.h"
+#include "ImplicitArgumentConversion.h"
 #include "RedundantSmartptrGet.h"
 #include "UseOverride.h"
 
@@ -28,6 +29,9 @@
         "misc-bool-pointer-implicit-conversion",
         new ClangTidyCheckFactory<BoolPointerImplicitConversion>());
     CheckFactories.addCheckFactory(
+        "misc-implicit-argument-conversion",
+        new ClangTidyCheckFactory<ImplicitArgumentConversion>());
+    CheckFactories.addCheckFactory(
         "misc-redundant-smartptr-get",
         new ClangTidyCheckFactory<RedundantSmartptrGet>());
     CheckFactories.addCheckFactory(
Index: test/clang-tidy/misc-implicit-argument-conversion.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/misc-implicit-argument-conversion.cpp
@@ -0,0 +1,14 @@
+// RUN: clang-tidy %s --checks="-*,misc-implicit-argument-conversion" -- 2>&1 | FileCheck %s
+
+void F(int, double);
+
+void foo() {
+// CHECK: multiple implicit literal conversions
+  F(1.0, 3);
+
+  F(1.0, 1.0); // no-warning
+  F(3, 1.0); // no-warning
+  F(true, false); // no-warning
+  F(0, 'c'); // no-warning
+}
+