diff --git a/clang/include/clang/Basic/Diagnostic.h b/clang/include/clang/Basic/Diagnostic.h
--- a/clang/include/clang/Basic/Diagnostic.h
+++ b/clang/include/clang/Basic/Diagnostic.h
@@ -545,6 +545,7 @@
   DiagnosticsEngine &operator=(const DiagnosticsEngine &) = delete;
   ~DiagnosticsEngine();
 
+  friend void DiagnosticsTestHelper(DiagnosticsEngine &);
   LLVM_DUMP_METHOD void dump() const;
   LLVM_DUMP_METHOD void dump(StringRef DiagName) const;
 
@@ -891,9 +892,9 @@
     LastDiagLevel = Other.LastDiagLevel;
   }
 
-  /// Reset the state of the diagnostic object to its initial
-  /// configuration.
-  void Reset();
+  /// Reset the state of the diagnostic object to its initial configuration.
+  /// \param[in] soft - if true, doesn't reset the diagnostic mappings and state
+  void Reset(bool soft = false);
 
   //===--------------------------------------------------------------------===//
   // DiagnosticsEngine classification and reporting interfaces.
diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -130,7 +130,7 @@
   return true;
 }
 
-void DiagnosticsEngine::Reset() {
+void DiagnosticsEngine::Reset(bool soft /*=false*/) {
   ErrorOccurred = false;
   UncompilableErrorOccurred = false;
   FatalErrorOccurred = false;
@@ -145,15 +145,17 @@
   LastDiagLevel = DiagnosticIDs::Ignored;
   DelayedDiagID = 0;
 
-  // Clear state related to #pragma diagnostic.
-  DiagStates.clear();
-  DiagStatesByLoc.clear();
-  DiagStateOnPushStack.clear();
+  if (!soft) {
+    // Clear state related to #pragma diagnostic.
+    DiagStates.clear();
+    DiagStatesByLoc.clear();
+    DiagStateOnPushStack.clear();
 
-  // Create a DiagState and DiagStatePoint representing diagnostic changes
-  // through command-line.
-  DiagStates.emplace_back();
-  DiagStatesByLoc.appendFirst(&DiagStates.back());
+    // Create a DiagState and DiagStatePoint representing diagnostic changes
+    // through command-line.
+    DiagStates.emplace_back();
+    DiagStatesByLoc.appendFirst(&DiagStates.back());
+  }
 }
 
 void DiagnosticsEngine::SetDelayedDiagnostic(unsigned DiagID, StringRef Arg1,
diff --git a/clang/lib/Interpreter/IncrementalParser.cpp b/clang/lib/Interpreter/IncrementalParser.cpp
--- a/clang/lib/Interpreter/IncrementalParser.cpp
+++ b/clang/lib/Interpreter/IncrementalParser.cpp
@@ -203,8 +203,8 @@
       }
     }
 
-    // FIXME: Do not reset the pragma handlers.
-    Diags.Reset();
+    Diags.Reset(/*soft=*/true);
+    Diags.getClient()->clear();
     return llvm::make_error<llvm::StringError>("Parsing failed.",
                                                std::error_code());
   }
diff --git a/clang/tools/clang-repl/ClangRepl.cpp b/clang/tools/clang-repl/ClangRepl.cpp
--- a/clang/tools/clang-repl/ClangRepl.cpp
+++ b/clang/tools/clang-repl/ClangRepl.cpp
@@ -48,6 +48,23 @@
   exit(GenCrashDiag ? 70 : 1);
 }
 
+// If we are running with -verify a reported has to be returned as unsuccess.
+// This is relevant especially for the test suite.
+static int checkDiagErrors(const clang::CompilerInstance *CI) {
+  unsigned Errs = CI->getDiagnostics().getClient()->getNumErrors();
+  if (CI->getDiagnosticOpts().VerifyDiagnostics) {
+    // If there was an error that came from the verifier we must return 1 as
+    // an exit code for the process. This will make the test fail as expected.
+    clang::DiagnosticConsumer *Client = CI->getDiagnostics().getClient();
+    Client->EndSourceFile();
+    Errs = Client->getNumErrors();
+
+    // The interpreter expects BeginSourceFile/EndSourceFiles to be balanced.
+    Client->BeginSourceFile(CI->getLangOpts(), &CI->getPreprocessor());
+  }
+  return Errs ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
 llvm::ExitOnError ExitOnErr;
 int main(int argc, const char **argv) {
   ExitOnErr.setBanner("clang-repl: ");
@@ -106,5 +123,5 @@
 
   llvm::llvm_shutdown();
 
-  return 0;
+  return checkDiagErrors(Interp->getCompilerInstance());
 }
diff --git a/clang/unittests/Basic/DiagnosticTest.cpp b/clang/unittests/Basic/DiagnosticTest.cpp
--- a/clang/unittests/Basic/DiagnosticTest.cpp
+++ b/clang/unittests/Basic/DiagnosticTest.cpp
@@ -14,6 +14,15 @@
 using namespace llvm;
 using namespace clang;
 
+void clang::DiagnosticsTestHelper(DiagnosticsEngine &diag) {
+  unsigned delayedDiagID = 0U;
+
+  EXPECT_EQ(diag.DelayedDiagID, delayedDiagID);
+  EXPECT_FALSE(diag.DiagStates.empty());
+  EXPECT_TRUE(diag.DiagStatesByLoc.empty());
+  EXPECT_TRUE(diag.DiagStateOnPushStack.empty());
+}
+
 namespace {
 
 // Check that DiagnosticErrorTrap works with SuppressAllDiagnostics.
@@ -71,6 +80,32 @@
     EXPECT_EQ(Diags.getNumWarnings(), FatalsAsError);
   }
 }
+
+// Check that soft RESET works as intended
+TEST(DiagnosticTest, softReset) {
+  DiagnosticsEngine Diags(new DiagnosticIDs(), new DiagnosticOptions,
+                          new IgnoringDiagConsumer());
+
+  unsigned numWarnings = 0U, numErrors = 0U;
+
+  Diags.Reset(true);
+  // Check For ErrorOccurred and TrapNumErrorsOccurred
+  EXPECT_FALSE(Diags.hasErrorOccurred());
+  EXPECT_FALSE(Diags.hasFatalErrorOccurred());
+  EXPECT_FALSE(Diags.hasUncompilableErrorOccurred());
+  // Check for UnrecoverableErrorOccurred and TrapNumUnrecoverableErrorsOccurred
+  EXPECT_FALSE(Diags.hasUnrecoverableErrorOccurred());
+
+  EXPECT_EQ(Diags.getNumWarnings(), numWarnings);
+  EXPECT_EQ(Diags.getNumErrors(), numErrors);
+
+  // Check for private variables of DiagnosticsEngine differentiating soft reset
+  DiagnosticsTestHelper(Diags);
+
+  EXPECT_FALSE(Diags.isDiagnosticInFlight());
+  EXPECT_TRUE(Diags.isLastDiagnosticIgnored());
+}
+
 TEST(DiagnosticTest, diagnosticError) {
   DiagnosticsEngine Diags(new DiagnosticIDs(), new DiagnosticOptions,
                           new IgnoringDiagConsumer());