diff --git a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
index ad38bcf51..e436c50a4 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular.h
@@ -269,10 +269,13 @@ struct general_product_to_triangular_selector<MatrixType,ProductType,UpLo,false>
     enum {
       IsRowMajor = (internal::traits<MatrixType>::Flags&RowMajorBit) ? 1 : 0,
       LhsIsRowMajor = _ActualLhs::Flags&RowMajorBit ? 1 : 0,
-      RhsIsRowMajor = _ActualRhs::Flags&RowMajorBit ? 1 : 0
+      RhsIsRowMajor = _ActualRhs::Flags&RowMajorBit ? 1 : 0,
+      SkipDiag = (UpLo&(UnitDiag|ZeroDiag))!=0
     };
 
     Index size = mat.cols();
+    if(SkipDiag)
+      size--;
     Index depth = actualLhs.cols();
 
     typedef internal::gemm_blocking_space<IsRowMajor ? RowMajor : ColMajor,typename Lhs::Scalar,typename Rhs::Scalar,
@@ -283,10 +286,11 @@ struct general_product_to_triangular_selector<MatrixType,ProductType,UpLo,false>
     internal::general_matrix_matrix_triangular_product<Index,
       typename Lhs::Scalar, LhsIsRowMajor ? RowMajor : ColMajor, LhsBlasTraits::NeedToConjugate,
       typename Rhs::Scalar, RhsIsRowMajor ? RowMajor : ColMajor, RhsBlasTraits::NeedToConjugate,
-      IsRowMajor ? RowMajor : ColMajor, UpLo>
+      IsRowMajor ? RowMajor : ColMajor, UpLo&(Lower|Upper)>
       ::run(size, depth,
-            &actualLhs.coeffRef(0,0), actualLhs.outerStride(), &actualRhs.coeffRef(0,0), actualRhs.outerStride(),
-            mat.data(), mat.outerStride(), actualAlpha, blocking);
+            &actualLhs.coeffRef(SkipDiag&&(UpLo&Lower)==Lower ? 1 : 0,0), actualLhs.outerStride(),
+            &actualRhs.coeffRef(0,SkipDiag&&(UpLo&Upper)==Upper ? 1 : 0), actualRhs.outerStride(),
+            mat.data() + (SkipDiag ? (bool(IsRowMajor) != ((UpLo&Lower)==Lower) ? 1 : mat.outerStride() ) : 0), mat.outerStride(), actualAlpha, blocking);
   }
 };
 
@@ -294,6 +298,7 @@ template<typename MatrixType, unsigned int UpLo>
 template<typename ProductType>
 EIGEN_DEVICE_FUNC TriangularView<MatrixType,UpLo>& TriangularViewImpl<MatrixType,UpLo,Dense>::_assignProduct(const ProductType& prod, const Scalar& alpha, bool beta)
 {
+  EIGEN_STATIC_ASSERT((UpLo&UnitDiag)==0, WRITING_TO_TRIANGULAR_PART_WITH_UNIT_DIAGONAL_IS_NOT_SUPPORTED);
   eigen_assert(derived().nestedExpression().rows() == prod.rows() && derived().cols() == prod.cols());
 
   general_product_to_triangular_selector<MatrixType, ProductType, UpLo, internal::traits<ProductType>::InnerSize==1>::run(derived().nestedExpression().const_cast_derived(), prod, alpha, beta);
diff --git a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular_BLAS.h b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular_BLAS.h
index 5b7c15cca..41e18ff07 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrixTriangular_BLAS.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrixTriangular_BLAS.h
@@ -52,7 +52,7 @@ struct general_matrix_matrix_triangular_product<Index,Scalar,LhsStorageOrder,Con
   static EIGEN_STRONG_INLINE void run(Index size, Index depth,const Scalar* lhs, Index lhsStride, \
                           const Scalar* rhs, Index rhsStride, Scalar* res, Index resStride, Scalar alpha, level3_blocking<Scalar, Scalar>& blocking) \
   { \
-    if (lhs==rhs) { \
+    if ( lhs==rhs && ((UpLo&(Lower|Upper)==UpLo)) ) { \
       general_matrix_matrix_rankupdate<Index,Scalar,LhsStorageOrder,ConjugateLhs,ColMajor,UpLo> \
       ::run(size,depth,lhs,lhsStride,rhs,rhsStride,res,resStride,alpha,blocking); \
     } else { \
diff --git a/test/product_mmtr.cpp b/test/product_mmtr.cpp
index f6e4bb1ae..d3e24b012 100644
--- a/test/product_mmtr.cpp
+++ b/test/product_mmtr.cpp
@@ -1,7 +1,7 @@
 // This file is part of Eigen, a lightweight C++ template library
 // for linear algebra.
 //
-// Copyright (C) 2010 Gael Guennebaud <gael.guennebaud@inria.fr>
+// Copyright (C) 2010-2017 Gael Guennebaud <gael.guennebaud@inria.fr>
 //
 // This Source Code Form is subject to the terms of the Mozilla
 // Public License v. 2.0. If a copy of the MPL was not distributed
@@ -10,12 +10,19 @@
 #include "main.h"
 
 #define CHECK_MMTR(DEST, TRI, OP) {                   \
+    ref3 = DEST;                                      \
     ref2 = ref1 = DEST;                               \
     DEST.template triangularView<TRI>() OP;           \
     ref1 OP;                                          \
     ref2.template triangularView<TRI>()               \
       = ref1.template triangularView<TRI>();          \
     VERIFY_IS_APPROX(DEST,ref2);                      \
+    \
+    DEST = ref3;                                      \
+    ref3 = ref2;                                      \
+    ref3.diagonal() = DEST.diagonal();                \
+    DEST.template triangularView<TRI|ZeroDiag>() OP;  \
+    VERIFY_IS_APPROX(DEST,ref3);                      \
   }
 
 template<typename Scalar> void mmtr(int size)
@@ -27,7 +34,7 @@ template<typename Scalar> void mmtr(int size)
   
   MatrixColMaj matc = MatrixColMaj::Zero(size, size);
   MatrixRowMaj matr = MatrixRowMaj::Zero(size, size);
-  MatrixColMaj ref1(size, size), ref2(size, size);
+  MatrixColMaj ref1(size, size), ref2(size, size), ref3(size,size);
   
   MatrixColMaj soc(size,othersize); soc.setRandom();
   MatrixColMaj osc(othersize,size); osc.setRandom();