Index: clang/lib/AST/Interp/ByteCodeExprGen.h
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.h
+++ clang/lib/AST/Interp/ByteCodeExprGen.h
@@ -253,6 +253,15 @@
     return (*InitFn)();
   }
 
+  /// Returns the CXXRecordDecl for the type of the given expression,
+  /// or nullptr if no such decl exists.
+  const CXXRecordDecl * getRecordDecl(const Expr *E) const {
+    QualType T = E->getType();
+    if (const auto *RD = T->getPointeeCXXRecordDecl())
+      return RD;
+   return T->getAsCXXRecordDecl();
+  }
+
 protected:
   /// Variable to storage mapping.
   llvm::DenseMap<const ValueDecl *, Scope::Local> Locals;
Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -107,6 +107,21 @@
         });
   }
 
+  case CK_UncheckedDerivedToBase: {
+    if (!this->visit(SubExpr))
+      return false;
+
+    const CXXRecordDecl *FromDecl = getRecordDecl(SubExpr);
+    assert(FromDecl);
+    const CXXRecordDecl *ToDecl = getRecordDecl(CE);
+    assert(ToDecl);
+    const Record *R = getRecord(FromDecl);
+    const Record::Base *ToBase = R->getBase(ToDecl);
+    assert(ToBase);
+
+    return this->emitGetPtrBase(ToBase->Offset, CE);
+  }
+
   case CK_ArrayToPointerDecay:
   case CK_AtomicToNonAtomic:
   case CK_ConstructorConversion:
Index: clang/lib/AST/Interp/ByteCodeStmtGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeStmtGen.cpp
+++ clang/lib/AST/Interp/ByteCodeStmtGen.cpp
@@ -100,31 +100,45 @@
     const Record *R = this->getRecord(RD);
 
     for (const auto *Init : Ctor->inits()) {
-      const FieldDecl *Member = Init->getMember();
       const Expr *InitExpr = Init->getInit();
-      const Record::Field *F = R->getField(Member);
-
-      if (Optional<PrimType> T = this->classify(InitExpr->getType())) {
-        if (!this->emitThis(InitExpr))
-          return false;
-
-        if (!this->visit(InitExpr))
-          return false;
-
-        if (!this->emitInitField(*T, F->Offset, InitExpr))
+      if (const FieldDecl *Member = Init->getMember()) {
+        const Record::Field *F = R->getField(Member);
+
+        if (Optional<PrimType> T = this->classify(InitExpr->getType())) {
+          if (!this->emitThis(InitExpr))
+            return false;
+
+          if (!this->visit(InitExpr))
+            return false;
+
+          if (!this->emitInitField(*T, F->Offset, InitExpr))
+            return false;
+        } else {
+          // Non-primitive case. Get a pointer to the field-to-initialize
+          // on the stack and call visitInitialzer() for it.
+          if (!this->emitThis(InitExpr))
+            return false;
+
+          if (!this->emitGetPtrField(F->Offset, InitExpr))
+            return false;
+
+          if (!this->visitInitializer(InitExpr))
+            return false;
+
+          if (!this->emitPopPtr(InitExpr))
+            return false;
+        }
+      } else if (const Type *Base = Init->getBaseClass()) {
+        // Base class initializer.
+        // Get This Base and call initializer on it.
+        auto *BaseDecl = Base->getAsCXXRecordDecl();
+        assert(BaseDecl);
+        const Record::Base *B = R->getBase(BaseDecl);
+        assert(B);
+        if (!this->emitGetPtrThisBase(B->Offset, InitExpr))
           return false;
-      } else {
-        // Non-primitive case. Get a pointer to the field-to-initialize
-        // on the stack and call visitInitialzer() for it.
-        if (!this->emitThis(InitExpr))
-          return false;
-
-        if (!this->emitGetPtrField(F->Offset, InitExpr))
-          return false;
-
         if (!this->visitInitializer(InitExpr))
           return false;
-
         if (!this->emitPopPtr(InitExpr))
           return false;
       }
Index: clang/test/AST/Interp/records.cpp
===================================================================
--- clang/test/AST/Interp/records.cpp
+++ clang/test/AST/Interp/records.cpp
@@ -1,9 +1,6 @@
 // RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
 // RUN: %clang_cc1 -verify=ref %s
 
-// ref-no-diagnostics
-// expected-no-diagnostics
-
 struct BoolPair {
   bool first;
   bool second;
@@ -157,3 +154,57 @@
 static_assert(LT2.v[0].second == false, "");
 static_assert(LT2.v[2].first == true, "");
 static_assert(LT2.v[2].second == false, "");
+
+class Base {
+public:
+  int i;
+  constexpr Base() : i(10) {}
+  constexpr Base(int i) : i(i) {}
+};
+
+class A : public Base {
+public:
+  constexpr A() : Base(100) {}
+  constexpr A(int a) : Base(a) {}
+};
+constexpr A a{};
+static_assert(a.i == 100, "");
+constexpr A a2{12};
+static_assert(a2.i == 12, "");
+static_assert(a2.i == 200, ""); // ref-error {{static assertion failed}} \
+                                // ref-note {{evaluates to '12 == 200'}} \
+                                // expected-error {{static assertion failed}} \
+                                // expected-note {{evaluates to '12 == 200'}}
+
+namespace MI {
+  class A {
+  public:
+    int a;
+    constexpr A(int a) : a(a) {}
+  };
+
+  class B {
+  public:
+    int b;
+    constexpr B(int b) : b(b) {}
+  };
+
+  class C : public A, public B {
+  public:
+    constexpr C() : A(10), B(20) {}
+  };
+  constexpr C c = {};
+  static_assert(c.a == 10);
+  static_assert(c.b == 20);
+
+
+  class D : private A, private B {
+    public:
+    constexpr D() : A(20), B(30) {}
+    constexpr int getA() const { return a; }
+    constexpr int getB() const { return b; }
+  };
+  constexpr D d = {};
+  static_assert(d.getA() == 20);
+  static_assert(d.getB() == 30);
+};