Index: tools/libclang/CIndex.cpp
===================================================================
--- tools/libclang/CIndex.cpp
+++ tools/libclang/CIndex.cpp
@@ -3505,11 +3505,6 @@
         llvm::makeArrayRef(unsaved_files, num_unsaved_files), options, out_TU);
   };
 
-  if (getenv("LIBCLANG_NOTHREADS")) {
-    ParseTranslationUnitImpl();
-    return result;
-  }
-
   llvm::CrashRecoveryContext CRC;
 
   if (!RunSafely(CRC, ParseTranslationUnitImpl)) {
@@ -3918,8 +3913,7 @@
     result = clang_saveTranslationUnit_Impl(TU, FileName, options);
   };
 
-  if (!CXXUnit->getDiagnostics().hasUnrecoverableErrorOccurred() ||
-      getenv("LIBCLANG_NOTHREADS")) {
+  if (!CXXUnit->getDiagnostics().hasUnrecoverableErrorOccurred()) {
     SaveTranslationUnitImpl();
 
     if (getenv("LIBCLANG_RESOURCE_USAGE"))
@@ -4042,11 +4036,6 @@
         TU, llvm::makeArrayRef(unsaved_files, num_unsaved_files), options);
   };
 
-  if (getenv("LIBCLANG_NOTHREADS")) {
-    ReparseTranslationUnitImpl();
-    return result;
-  }
-
   llvm::CrashRecoveryContext CRC;
 
   if (!RunSafely(CRC, ReparseTranslationUnitImpl)) {
@@ -8131,7 +8120,7 @@
                unsigned Size) {
   if (!Size)
     Size = GetSafetyThreadStackSize();
-  if (Size)
+  if (Size && !getenv("LIBCLANG_NOTHREADS"))
     return CRC.RunSafelyOnThread(Fn, Size);
   return CRC.RunSafely(Fn);
 }
Index: tools/libclang/CIndexCodeCompletion.cpp
===================================================================
--- tools/libclang/CIndexCodeCompletion.cpp
+++ tools/libclang/CIndexCodeCompletion.cpp
@@ -806,11 +806,6 @@
         llvm::makeArrayRef(unsaved_files, num_unsaved_files), options);
   };
 
-  if (getenv("LIBCLANG_NOTHREADS")) {
-    CodeCompleteAtImpl();
-    return result;
-  }
-
   llvm::CrashRecoveryContext CRC;
 
   if (!RunSafely(CRC, CodeCompleteAtImpl)) {
Index: tools/libclang/Indexing.cpp
===================================================================
--- tools/libclang/Indexing.cpp
+++ tools/libclang/Indexing.cpp
@@ -879,11 +879,6 @@
         TU_options);
   };
 
-  if (getenv("LIBCLANG_NOTHREADS")) {
-    IndexSourceFileImpl();
-    return result;
-  }
-
   llvm::CrashRecoveryContext CRC;
 
   if (!RunSafely(CRC, IndexSourceFileImpl)) {
@@ -933,11 +928,6 @@
         index_options, TU);
   };
 
-  if (getenv("LIBCLANG_NOTHREADS")) {
-    IndexTranslationUnitImpl();
-    return result;
-  }
-
   llvm::CrashRecoveryContext CRC;
 
   if (!RunSafely(CRC, IndexTranslationUnitImpl)) {