diff --git a/flang/include/flang/Frontend/CompilerInstance.h b/flang/include/flang/Frontend/CompilerInstance.h
--- a/flang/include/flang/Frontend/CompilerInstance.h
+++ b/flang/include/flang/Frontend/CompilerInstance.h
@@ -13,6 +13,7 @@
 #include "flang/Frontend/PreprocessorOptions.h"
 #include "flang/Parser/parsing.h"
 #include "flang/Parser/provenance.h"
+#include "flang/Semantics/runtime-type-info.h"
 #include "flang/Semantics/semantics.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -47,6 +48,8 @@
 
   std::unique_ptr<Fortran::semantics::Semantics> semantics_;
 
+  std::unique_ptr<Fortran::semantics::RuntimeDerivedTypeTables> rtTyTables_;
+
   /// The stream for diagnostics from Semantics
   llvm::raw_ostream *semaOutputStream_ = &llvm::errs();
 
@@ -129,6 +132,16 @@
     semantics_ = std::move(semantics);
   }
 
+  void setRtTyTables(
+      std::unique_ptr<Fortran::semantics::RuntimeDerivedTypeTables> tables) {
+    rtTyTables_ = std::move(tables);
+  }
+
+  Fortran::semantics::RuntimeDerivedTypeTables &getRtTyTables() {
+    assert(rtTyTables_ && "Missing runtime derived type tables!");
+    return *rtTyTables_;
+  }
+
   /// }
   /// @name High-Level Operations
   /// {
diff --git a/flang/include/flang/Frontend/FrontendAction.h b/flang/include/flang/Frontend/FrontendAction.h
--- a/flang/include/flang/Frontend/FrontendAction.h
+++ b/flang/include/flang/Frontend/FrontendAction.h
@@ -112,6 +112,10 @@
   // Run semantic checks for the current input file. Return False if fatal
   // errors are reported, True otherwise.
   bool RunSemanticChecks();
+  // Generate run-time type information for derived types. This may lead to new
+  // semantic errors. Return False if fatal errors are reported, True
+  // otherwise.
+  bool GenerateRtTypeTables();
 
   // Report fatal semantic errors. Return True if present, false otherwise.
   bool reportFatalSemanticErrors();
diff --git a/flang/include/flang/Frontend/FrontendActions.h b/flang/include/flang/Frontend/FrontendActions.h
--- a/flang/include/flang/Frontend/FrontendActions.h
+++ b/flang/include/flang/Frontend/FrontendActions.h
@@ -133,7 +133,12 @@
 // PrescanAndSemaDebug Actions
 //
 // These actions will parse the input, run the semantic checks and execute
-// their actions regardless of whether any semantic errors are found.
+// their actions _regardless of_ whether any semantic errors have been found.
+// This can be useful when adding new languge feature and when you wish to
+// investigate compiler output (e.g. the parse tree) despite any semantinc
+// errors.
+//
+// NOTE: Use with care and for development only!
 //===----------------------------------------------------------------------===//
 class PrescanAndSemaDebugAction : public FrontendAction {
 
diff --git a/flang/lib/Frontend/FrontendAction.cpp b/flang/lib/Frontend/FrontendAction.cpp
--- a/flang/lib/Frontend/FrontendAction.cpp
+++ b/flang/lib/Frontend/FrontendAction.cpp
@@ -180,6 +180,21 @@
   return true;
 }
 
+bool FrontendAction::GenerateRtTypeTables() {
+  instance().setRtTyTables(
+      std::make_unique<Fortran::semantics::RuntimeDerivedTypeTables>(
+          BuildRuntimeDerivedTypeTables(
+              instance().invocation().semanticsContext())));
+
+  // The runtime derived type information table builder may find additional
+  // semantic errors. Report them.
+  if (reportFatalSemanticErrors()) {
+    return false;
+  }
+
+  return true;
+}
+
 template <unsigned N>
 bool FrontendAction::reportFatalErrors(const char (&message)[N]) {
   if (!instance_->parsing().messages().empty() &&
diff --git a/flang/lib/Frontend/FrontendActions.cpp b/flang/lib/Frontend/FrontendActions.cpp
--- a/flang/lib/Frontend/FrontendActions.cpp
+++ b/flang/lib/Frontend/FrontendActions.cpp
@@ -47,12 +47,18 @@
 }
 
 bool PrescanAndSemaAction::BeginSourceFileAction() {
-  return RunPrescan() && RunParse() && RunSemanticChecks();
+  return RunPrescan() && RunParse() && RunSemanticChecks() &&
+      GenerateRtTypeTables();
 }
 
 bool PrescanAndSemaDebugAction::BeginSourceFileAction() {
-  // Semantic checks are made to succeed unconditionally.
-  return RunPrescan() && RunParse() && (RunSemanticChecks() || true);
+  // This is a "debug" action for development purposes. To facilitate this, the
+  // semantic checks are made to succeed unconditionally to prevent this action
+  // from exiting early (i.e. in the presence of semantic errors). We should
+  // never do this in actions intended for end-users or otherwise regular
+  // compiler workflows!
+  return RunPrescan() && RunParse() && (RunSemanticChecks() || true) &&
+      (GenerateRtTypeTables() || true);
 }
 
 bool CodeGenAction::BeginSourceFileAction() {
@@ -218,16 +224,8 @@
 
 void DebugDumpSymbolsAction::ExecuteAction() {
   CompilerInstance &ci = this->instance();
-  auto &semantics = ci.semantics();
 
-  auto tables{Fortran::semantics::BuildRuntimeDerivedTypeTables(
-      instance().invocation().semanticsContext())};
-  // The runtime derived type information table builder may find and report
-  // semantic errors. So it is important that we report them _after_
-  // BuildRuntimeDerivedTypeTables is run.
-  reportFatalSemanticErrors();
-
-  if (!tables.schemata) {
+  if (!ci.getRtTyTables().schemata) {
     unsigned DiagID =
         ci.diagnostics().getCustomDiagID(clang::DiagnosticsEngine::Error,
             "could not find module file for __fortran_type_info");
@@ -236,7 +234,7 @@
   }
 
   // Dump symbols
-  semantics.DumpSymbols(llvm::outs());
+  ci.semantics().DumpSymbols(llvm::outs());
 }
 
 void DebugDumpAllAction::ExecuteAction() {
@@ -250,15 +248,7 @@
   Fortran::parser::DumpTree(
       llvm::outs(), parseTree, &ci.invocation().asFortran());
 
-  auto &semantics = ci.semantics();
-  auto tables{Fortran::semantics::BuildRuntimeDerivedTypeTables(
-      instance().invocation().semanticsContext())};
-  // The runtime derived type information table builder may find and report
-  // semantic errors. So it is important that we report them _after_
-  // BuildRuntimeDerivedTypeTables is run.
-  reportFatalSemanticErrors();
-
-  if (!tables.schemata) {
+  if (!ci.getRtTyTables().schemata) {
     unsigned DiagID =
         ci.diagnostics().getCustomDiagID(clang::DiagnosticsEngine::Error,
             "could not find module file for __fortran_type_info");
@@ -270,7 +260,7 @@
   llvm::outs() << "=====================";
   llvm::outs() << " Flang: symbols dump ";
   llvm::outs() << "=====================\n";
-  semantics.DumpSymbols(llvm::outs());
+  ci.semantics().DumpSymbols(llvm::outs());
 }
 
 void DebugDumpParseTreeNoSemaAction::ExecuteAction() {