diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -3491,6 +3491,51 @@
     Actions.push_back(
         C.MakeAction<IfsMergeJobAction>(MergerInputs, types::TY_Image));
 
+  if (Arg *A = Args.getLastArg(options::OPT_emit_interface_stubs)) {
+    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> PhaseList;
+    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> &PL = PhaseList;
+    types::getCompilationPhases(types::TY_IFS_CPP, PL);
+
+    ActionList MergerInputs;
+
+    for (auto &I : Inputs) {
+      types::ID InputType = I.first;
+      const Arg *InputArg = I.second;
+
+      if (InputType == types::TY_IFS)
+        continue;
+
+      Action *Current = C.MakeAction<InputAction>(*InputArg, InputType);
+
+      for (phases::ID Phase : PL) {
+        if (Phase == phases::IfsMerge) {
+          assert(Phase == PL.back() &&
+                 "merging must be final compilation step.");
+          MergerInputs.push_back(Current);
+          Current = nullptr;
+          break;
+        }
+
+        if (Phase == phases::Compile) {
+          Current = C.MakeAction<CompileJobAction>(Current, types::TY_IFS_CPP);
+          continue;
+        }
+
+        llvm_unreachable(
+            "IFS Pipeline can only consist of Compile followed by IfsMerge.");
+      }
+
+      // If we ended with something, add to the output list.
+      if (Current)
+        Actions.push_back(Current);
+    }
+
+    // Add an interface stubs merge action if necessary.
+    if (!MergerInputs.empty())
+      Actions.push_back(
+          C.MakeAction<IfsMergeJobAction>(MergerInputs, types::TY_Image));
+  }
+
   // If --print-supported-cpus, -mcpu=? or -mtune=? is specified, build a custom
   // Compile phase that prints out supported cpu models and quits.
   if (Arg *A = Args.getLastArg(options::OPT_print_supported_cpus)) {
@@ -3592,8 +3637,6 @@
       return C.MakeAction<CompileJobAction>(Input, types::TY_ModuleFile);
     if (Args.hasArg(options::OPT_verify_pch))
       return C.MakeAction<VerifyPCHJobAction>(Input, types::TY_Nothing);
-    if (Args.hasArg(options::OPT_emit_interface_stubs))
-      return C.MakeAction<CompileJobAction>(Input, types::TY_IFS_CPP);
     return C.MakeAction<CompileJobAction>(Input, types::TY_LLVM_BC);
   }
   case phases::Backend: {
@@ -3626,7 +3669,8 @@
   if (FinalOutput) {
     unsigned NumOutputs = 0;
     for (const Action *A : C.getActions())
-      if (A->getType() != types::TY_Nothing)
+      if (A->getType() != types::TY_Nothing &&
+          A->getKind() != Action::IfsMergeJobClass)
         ++NumOutputs;
 
     if (NumOutputs > 1) {
diff --git a/clang/lib/Driver/ToolChains/InterfaceStubs.cpp b/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
--- a/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
+++ b/clang/lib/Driver/ToolChains/InterfaceStubs.cpp
@@ -21,11 +21,29 @@
   std::string Merger = getToolChain().GetProgramPath(getShortName());
   llvm::opt::ArgStringList CmdArgs;
   CmdArgs.push_back("-action");
-  CmdArgs.push_back(Args.getLastArg(options::OPT_emit_merged_ifs)
-                        ? "write-ifs"
-                        : "write-bin");
+  const bool WriteBin = !Args.getLastArg(options::OPT_emit_merged_ifs);
+  CmdArgs.push_back(WriteBin ? "write-bin" : "write-ifs");
   CmdArgs.push_back("-o");
-  CmdArgs.push_back(Output.getFilename());
+
+  std::string OutputFilename = Output.getFilename();
+
+  // Normally we want to write to a side-car file ending in ".ifso" so for
+  // example if `clang -emit-interface-stubs -shared -o libhello.so` were
+  // invoked then we would like to get libhello.so and libhello.ifso. If the
+  // stdout stream is given as the output file (ie `-o -`), that is the one
+  // exception where we will just append to the same filestream as the normal
+  // output.
+  if (OutputFilename != "-") {
+    std::string DllFileExt = ".so";
+    size_t TrimedSize = OutputFilename.size() - DllFileExt.size();
+    if (OutputFilename.size() > DllFileExt.size() &&
+        std::equal(OutputFilename.begin() + TrimedSize, OutputFilename.end(),
+                   DllFileExt.begin()))
+      OutputFilename = OutputFilename.substr(0, TrimedSize);
+
+    OutputFilename += (WriteBin ? ".ifso" : ".ifs");
+  }
+  CmdArgs.push_back(Args.MakeArgString(OutputFilename.c_str()));
   for (const auto &Input : Inputs)
     CmdArgs.push_back(Input.getFilename());
   C.addCommand(std::make_unique<Command>(JA, *this, Args.MakeArgString(Merger),
diff --git a/clang/lib/Driver/Types.cpp b/clang/lib/Driver/Types.cpp
--- a/clang/lib/Driver/Types.cpp
+++ b/clang/lib/Driver/Types.cpp
@@ -330,22 +330,6 @@
     llvm::copy_if(PhaseList, std::back_inserter(P),
                   [](phases::ID Phase) { return Phase <= phases::Precompile; });
 
-  // Treat Interface Stubs like its own compilation mode.
-  else if (DAL.getLastArg(options::OPT_emit_interface_stubs)) {
-    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> IfsModePhaseList;
-    llvm::SmallVector<phases::ID, phases::MaxNumberOfPhases> &PL = PhaseList;
-    phases::ID LastPhase = phases::IfsMerge;
-    if (Id != types::TY_IFS) {
-      if (DAL.hasArg(options::OPT_c))
-        LastPhase = phases::Compile;
-      PL = IfsModePhaseList;
-      types::getCompilationPhases(types::TY_IFS_CPP, PL);
-    }
-    llvm::copy_if(PL, std::back_inserter(P), [&](phases::ID Phase) {
-      return Phase <= LastPhase;
-    });
-  }
-
   // -{fsyntax-only,-analyze,emit-ast} only run up to the compiler.
   else if (DAL.getLastArg(options::OPT_fsyntax_only) ||
            DAL.getLastArg(options::OPT_print_supported_cpus) ||
diff --git a/clang/test/InterfaceStubs/driver-test.c b/clang/test/InterfaceStubs/driver-test.c
--- a/clang/test/InterfaceStubs/driver-test.c
+++ b/clang/test/InterfaceStubs/driver-test.c
@@ -1,11 +1,13 @@
 // REQUIRES: x86-registered-target
 
-// RUN: %clang -target x86_64-unknown-linux-gnu -x c -o %t1.so -emit-interface-stubs %s %S/object.c %S/weak.cpp && \
-// RUN: llvm-nm %t1.so 2>&1 | FileCheck --check-prefix=CHECK-IFS %s
+// RUN: %clang -target x86_64-unknown-linux-gnu -x c -o %t1 -emit-interface-stubs %s %S/object.c %S/weak.cpp
+// RUN: llvm-nm %t1   2>&1 | FileCheck %s
+// RUN: llvm-nm %t1.ifso 2>&1 | FileCheck %s
 
-// CHECK-IFS-DAG: data
-// CHECK-IFS-DAG: foo
-// CHECK-IFS-DAG: strongFunc
-// CHECK-IFS-DAG: weakFunc
+// CHECK-DAG: data
+// CHECK-DAG: foo
+// CHECK-DAG: strongFunc
+// CHECK-DAG: weakFunc
 
 int foo(int bar) { return 42 + 1844; }
+int main() { return foo(23); }
diff --git a/clang/test/InterfaceStubs/windows.cpp b/clang/test/InterfaceStubs/windows.cpp
--- a/clang/test/InterfaceStubs/windows.cpp
+++ b/clang/test/InterfaceStubs/windows.cpp
@@ -1,6 +1,7 @@
 // REQUIRES: x86-registered-target
 // RUN: %clang_cc1 -triple x86_64-windows-msvc -o - %s -emit-interface-stubs | FileCheck -check-prefix=CHECK-CC1 %s
-// RUN: %clang -target x86_64-windows-msvc -o - %s -emit-interface-stubs -emit-merged-ifs | FileCheck -check-prefix=CHECK-IFS %s
+// RUN: %clang -target x86_64-windows-msvc -o - %s -emit-interface-stubs -emit-merged-ifs -c | FileCheck -check-prefix=CHECK-IFS %s
+// note: -c is added here to prevent clang from invoking link.exe
 
 // CHECK-CC1: Symbols:
 // CHECK-CC1-NEXT: ?helloWindowsMsvc@@YAHXZ