Index: include/clang/Sema/Sema.h
===================================================================
--- include/clang/Sema/Sema.h
+++ include/clang/Sema/Sema.h
@@ -4568,6 +4568,11 @@
   // of a ComparisonCategoryType enumerator.
   llvm::SmallBitVector FullyCheckedComparisonCategories;
 
+  ValueDecl *tryLookupCtorInitMemberDecl(CXXRecordDecl *ClassDecl,
+                                         CXXScopeSpec &SS,
+                                         ParsedType TemplateTypeTy,
+                                         IdentifierInfo *MemberOrBase);
+
 public:
   /// Lookup the specified comparison category types in the standard
   ///   library, an check the VarDecls possibly returned by the operator<=>
@@ -10254,6 +10259,12 @@
                                            SourceLocation Loc,
                                            ArrayRef<Expr *> Args,
                                            SourceLocation OpenParLoc);
+  QualType ProduceCtorInitMemberSignatureHelp(Scope *S, Decl *ConstructorDecl,
+                                              CXXScopeSpec SS,
+                                              ParsedType TemplateTypeTy,
+                                              ArrayRef<Expr *> ArgExprs,
+                                              IdentifierInfo *II,
+                                              SourceLocation OpenParLoc);
   void CodeCompleteInitializer(Scope *S, Decl *D);
   void CodeCompleteReturn(Scope *S);
   void CodeCompleteAfterIf(Scope *S);
@@ -10794,7 +10805,6 @@
   /// The template function declaration to be late parsed.
   Decl *D;
 };
-
 } // end namespace clang
 
 namespace llvm {
Index: lib/Parse/ParseDeclCXX.cpp
===================================================================
--- lib/Parse/ParseDeclCXX.cpp
+++ lib/Parse/ParseDeclCXX.cpp
@@ -3449,6 +3449,7 @@
   if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
     Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
 
+    // FIXME: Add support for signature help inside initializer lists.
     ExprResult InitList = ParseBraceInitializer();
     if (InitList.isInvalid())
       return true;
@@ -3466,7 +3467,20 @@
     // Parse the optional expression-list.
     ExprVector ArgExprs;
     CommaLocsTy CommaLocs;
-    if (Tok.isNot(tok::r_paren) && ParseExpressionList(ArgExprs, CommaLocs)) {
+    if (Tok.isNot(tok::r_paren) &&
+        ParseExpressionList(ArgExprs, CommaLocs, [&] {
+          QualType PreferredType = Actions.ProduceCtorInitMemberSignatureHelp(
+              getCurScope(), ConstructorDecl, SS, TemplateTypeTy, ArgExprs, II,
+              T.getOpenLocation());
+          CalledSignatureHelp = true;
+          Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+        })) {
+      if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
+        Actions.ProduceCtorInitMemberSignatureHelp(
+            getCurScope(), ConstructorDecl, SS, TemplateTypeTy, ArgExprs, II,
+            T.getOpenLocation());
+        CalledSignatureHelp = true;
+      }
       SkipUntil(tok::r_paren, StopAtSemi);
       return true;
     }
Index: lib/Sema/SemaCodeComplete.cpp
===================================================================
--- lib/Sema/SemaCodeComplete.cpp
+++ lib/Sema/SemaCodeComplete.cpp
@@ -4586,6 +4586,25 @@
   return ProduceSignatureHelp(*this, S, Results, Args.size(), OpenParLoc);
 }
 
+QualType Sema::ProduceCtorInitMemberSignatureHelp(
+    Scope *S, Decl *ConstructorDecl, CXXScopeSpec SS, ParsedType TemplateTypeTy,
+    ArrayRef<Expr *> ArgExprs, IdentifierInfo *II, SourceLocation OpenParLoc) {
+  if (!CodeCompleter)
+    return QualType();
+
+  CXXConstructorDecl *Constructor =
+      dyn_cast<CXXConstructorDecl>(ConstructorDecl);
+  if (!Constructor)
+    return QualType();
+  // FIXME: Add support for Base class constructors as well.
+  if (ValueDecl *MemberDecl = tryLookupCtorInitMemberDecl(
+          Constructor->getParent(), SS, TemplateTypeTy, II))
+    return ProduceConstructorSignatureHelp(getCurScope(), MemberDecl->getType(),
+                                           MemberDecl->getLocation(), ArgExprs,
+                                           OpenParLoc);
+  return QualType();
+}
+
 void Sema::CodeCompleteInitializer(Scope *S, Decl *D) {
   ValueDecl *VD = dyn_cast_or_null<ValueDecl>(D);
   if (!VD) {
Index: lib/Sema/SemaDeclCXX.cpp
===================================================================
--- lib/Sema/SemaDeclCXX.cpp
+++ lib/Sema/SemaDeclCXX.cpp
@@ -3777,6 +3777,22 @@
 
 }
 
+ValueDecl *Sema::tryLookupCtorInitMemberDecl(CXXRecordDecl *ClassDecl,
+                                             CXXScopeSpec &SS,
+                                             ParsedType TemplateTypeTy,
+                                             IdentifierInfo *MemberOrBase) {
+  if (SS.getScopeRep() || TemplateTypeTy)
+    return nullptr;
+  DeclContext::lookup_result Result = ClassDecl->lookup(MemberOrBase);
+  if (Result.empty())
+    return nullptr;
+  ValueDecl *Member;
+  if ((Member = dyn_cast<FieldDecl>(Result.front())) ||
+      (Member = dyn_cast<IndirectFieldDecl>(Result.front())))
+    return Member;
+  return nullptr;
+}
+
 /// Handle a C++ member initializer.
 MemInitResult
 Sema::BuildMemInitializer(Decl *ConstructorD,
@@ -3820,21 +3836,16 @@
   //   of a single identifier refers to the class member. A
   //   mem-initializer-id for the hidden base class may be specified
   //   using a qualified name. ]
-  if (!SS.getScopeRep() && !TemplateTypeTy) {
-    // Look for a member, first.
-    DeclContext::lookup_result Result = ClassDecl->lookup(MemberOrBase);
-    if (!Result.empty()) {
-      ValueDecl *Member;
-      if ((Member = dyn_cast<FieldDecl>(Result.front())) ||
-          (Member = dyn_cast<IndirectFieldDecl>(Result.front()))) {
-        if (EllipsisLoc.isValid())
-          Diag(EllipsisLoc, diag::err_pack_expansion_member_init)
-            << MemberOrBase
-            << SourceRange(IdLoc, Init->getSourceRange().getEnd());
 
-        return BuildMemberInitializer(Member, Init, IdLoc);
-      }
-    }
+  // Look for a member, first.
+  if (ValueDecl *Member = tryLookupCtorInitMemberDecl(
+          ClassDecl, SS, TemplateTypeTy, MemberOrBase)) {
+    if (EllipsisLoc.isValid())
+      Diag(EllipsisLoc, diag::err_pack_expansion_member_init)
+          << MemberOrBase
+          << SourceRange(IdLoc, Init->getSourceRange().getEnd());
+
+    return BuildMemberInitializer(Member, Init, IdLoc);
   }
   // It didn't name a member, so see if it names a class.
   QualType BaseType;
Index: test/CodeCompletion/ctor-initializer.cpp
===================================================================
--- test/CodeCompletion/ctor-initializer.cpp
+++ test/CodeCompletion/ctor-initializer.cpp
@@ -64,3 +64,27 @@
   // CHECK-CC8: COMPLETION: Pattern : member2(<#args#>
   int member1, member2;
 };
+
+struct Base2 {
+  Base2(int);
+};
+
+struct Composition1 {
+  Composition1() : b2_elem() {}
+  // RUN: %clang_cc1 -fsyntax-only -std=c++98 -code-completion-at=%s:73:28 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  // RUN: %clang_cc1 -fsyntax-only -std=c++14 -code-completion-at=%s:73:28 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  // CHECK-CC9: OVERLOAD: Base2(<#int#>)
+  // CHECK-CC9: OVERLOAD: Base2(<#const Base2 &#>)
+  // CHECK-CC9-NOT: OVERLOAD: Composition1
+  Composition1(Base2);
+  Base2 b2_elem;
+};
+
+struct Composition2 {
+  Composition2() : c1_elem(Base2(1)) {}
+  // RUN: %clang_cc1 -fsyntax-only -std=c++98 -code-completion-at=%s:84:34 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  // RUN: %clang_cc1 -fsyntax-only -std=c++14 -code-completion-at=%s:84:34 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  // RUN: %clang_cc1 -fsyntax-only -std=c++98 -code-completion-at=%s:84:35 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  // RUN: %clang_cc1 -fsyntax-only -std=c++14 -code-completion-at=%s:84:35 %s -o - | FileCheck -check-prefix=CHECK-CC9 %s
+  Composition1 c1_elem;
+};