diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2432,9 +2432,11 @@
                                           const LangStandard &S) {
   switch (IK.getLanguage()) {
   case Language::Unknown:
-  case Language::LLVM_IR:
     llvm_unreachable("should not parse language flags for this input");
 
+  case Language::LLVM_IR:
+    return false;
+
   case Language::C:
   case Language::ObjC:
   case Language::RenderScript:
@@ -2507,30 +2509,32 @@
     if (LangStd == LangStandard::lang_unspecified) {
       Diags.Report(diag::err_drv_invalid_value)
         << A->getAsString(Args) << A->getValue();
-      // Report supported standards with short description.
-      for (unsigned KindValue = 0;
-           KindValue != LangStandard::lang_unspecified;
-           ++KindValue) {
-        const LangStandard &Std = LangStandard::getLangStandardForKind(
-          static_cast<LangStandard::Kind>(KindValue));
-        if (IsInputCompatibleWithStandard(IK, Std)) {
-          auto Diag = Diags.Report(diag::note_drv_use_standard);
-          Diag << Std.getName() << Std.getDescription();
-          unsigned NumAliases = 0;
+      if (IK.getFormat() != InputKind::Precompiled) {
+        // Report supported standards with short description.
+        for (unsigned KindValue = 0;
+             KindValue != LangStandard::lang_unspecified;
+             ++KindValue) {
+          const LangStandard &Std = LangStandard::getLangStandardForKind(
+            static_cast<LangStandard::Kind>(KindValue));
+          if (IsInputCompatibleWithStandard(IK, Std)) {
+            auto Diag = Diags.Report(diag::note_drv_use_standard);
+            Diag << Std.getName() << Std.getDescription();
+            unsigned NumAliases = 0;
 #define LANGSTANDARD(id, name, lang, desc, features)
 #define LANGSTANDARD_ALIAS(id, alias) \
-          if (KindValue == LangStandard::lang_##id) ++NumAliases;
+            if (KindValue == LangStandard::lang_##id) ++NumAliases;
 #define LANGSTANDARD_ALIAS_DEPR(id, alias)
 #include "clang/Basic/LangStandards.def"
-          Diag << NumAliases;
+            Diag << NumAliases;
 #define LANGSTANDARD(id, name, lang, desc, features)
 #define LANGSTANDARD_ALIAS(id, alias) \
-          if (KindValue == LangStandard::lang_##id) Diag << alias;
+            if (KindValue == LangStandard::lang_##id) Diag << alias;
 #define LANGSTANDARD_ALIAS_DEPR(id, alias)
 #include "clang/Basic/LangStandards.def"
+          }
         }
       }
-    } else {
+    } else if (IK.getFormat() != InputKind::Precompiled) {
       // Valid standard, check to make sure language and standard are
       // compatible.
       const LangStandard &Std = LangStandard::getLangStandardForKind(LangStd);
@@ -2592,7 +2596,9 @@
   Opts.DeclareOpenCLBuiltins = Args.hasArg(OPT_fdeclare_opencl_builtins);
 
   llvm::Triple T(TargetOpts.Triple);
-  CompilerInvocation::setLangDefaults(Opts, IK, T, PPOpts, LangStd);
+  if (IK.getFormat() != InputKind::Precompiled &&
+      IK.getLanguage() != Language::LLVM_IR)
+    CompilerInvocation::setLangDefaults(Opts, IK, T, PPOpts, LangStd);
 
   // -cl-strict-aliasing needs to emit diagnostic in the case where CL > 1.0.
   // This option should be deprecated for CL > 1.0 because
@@ -3764,32 +3770,16 @@
   ParseHeaderSearchArgs(Res.getHeaderSearchOpts(), Args,
                         Res.getFileSystemOpts().WorkingDir);
   llvm::Triple T(Res.getTargetOpts().Triple);
-  if (DashX.getFormat() == InputKind::Precompiled ||
-      DashX.getLanguage() == Language::LLVM_IR) {
-    // ObjCAAutoRefCount and Sanitize LangOpts are used to setup the
-    // PassManager in BackendUtil.cpp. They need to be initializd no matter
-    // what the input type is.
-    if (Args.hasArg(OPT_fobjc_arc))
-      LangOpts.ObjCAutoRefCount = 1;
-    // PIClevel and PIELevel are needed during code generation and this should be
-    // set regardless of the input type.
-    LangOpts.PICLevel = getLastArgIntValue(Args, OPT_pic_level, 0, Diags);
-    LangOpts.PIE = Args.hasArg(OPT_pic_is_pie);
-    parseSanitizerKinds("-fsanitize=", Args.getAllArgValues(OPT_fsanitize_EQ),
-                        Diags, LangOpts.Sanitize);
-  } else {
-    // Other LangOpts are only initialized when the input is not AST or LLVM IR.
-    // FIXME: Should we really be calling this for an Language::Asm input?
-    ParseLangArgs(LangOpts, Args, DashX, Res.getTargetOpts(),
-                  Res.getPreprocessorOpts(), Diags);
-    if (Res.getFrontendOpts().ProgramAction == frontend::RewriteObjC)
-      LangOpts.ObjCExceptions = 1;
-    if (T.isOSDarwin() && DashX.isPreprocessed()) {
-      // Supress the darwin-specific 'stdlibcxx-not-found' diagnostic for
-      // preprocessed input as we don't expect it to be used with -std=libc++
-      // anyway.
-      Res.getDiagnosticOpts().Warnings.push_back("no-stdlibcxx-not-found");
-    }
+  // FIXME: Should we really be calling this for an Language::Asm input?
+  ParseLangArgs(LangOpts, Args, DashX, Res.getTargetOpts(),
+                Res.getPreprocessorOpts(), Diags);
+  if (Res.getFrontendOpts().ProgramAction == frontend::RewriteObjC)
+    LangOpts.ObjCExceptions = 1;
+  if (T.isOSDarwin() && DashX.isPreprocessed()) {
+    // Supress the darwin-specific 'stdlibcxx-not-found' diagnostic for
+    // preprocessed input as we don't expect it to be used with -std=libc++
+    // anyway.
+    Res.getDiagnosticOpts().Warnings.push_back("no-stdlibcxx-not-found");
   }
 
   if (Diags.isIgnored(diag::warn_profile_data_misexpect, SourceLocation()))