diff --git a/clang/include/clang/Frontend/CompilerInstance.h b/clang/include/clang/Frontend/CompilerInstance.h
--- a/clang/include/clang/Frontend/CompilerInstance.h
+++ b/clang/include/clang/Frontend/CompilerInstance.h
@@ -46,6 +46,7 @@
 class FrontendAction;
 class InMemoryModuleCache;
 class Module;
+class PPCallbacks;
 class Preprocessor;
 class Sema;
 class SourceManager;
@@ -180,6 +181,9 @@
   /// Force an output buffer.
   std::unique_ptr<llvm::raw_pwrite_stream> OutputStream;
 
+  /// Additional PPCallbacks to add to the created preprocessor.
+  std::unique_ptr<PPCallbacks> AdditionalPPCallbacks;
+
   CompilerInstance(const CompilerInstance &) = delete;
   void operator=(const CompilerInstance &) = delete;
 public:
@@ -247,6 +251,10 @@
     BuildGlobalModuleIndex = Build;
   }
 
+  /// Set the additional PP callbacks that will be added to the created
+  /// preprocessor.
+  void setAdditionalPPCallbacks(std::unique_ptr<PPCallbacks> PPC);
+
   /// }
   /// @name Forwarding Methods
   /// {
diff --git a/clang/include/clang/Lex/DependencyDirectivesSourceMinimizer.h b/clang/include/clang/Lex/DependencyDirectivesSourceMinimizer.h
--- a/clang/include/clang/Lex/DependencyDirectivesSourceMinimizer.h
+++ b/clang/include/clang/Lex/DependencyDirectivesSourceMinimizer.h
@@ -66,6 +66,24 @@
   Token(TokenKind K, int Offset) : K(K), Offset(Offset) {}
 };
 
+/// Simplified token range to track the range of a potentially skippable PP
+/// directive.
+struct SkippedRange {
+  /// Offset into the output byte stream of where the skipped directive begins.
+  int Offset;
+
+  /// The number of bytes that can be skipped before the preprocessing must
+  /// resume.
+  int Length;
+};
+
+/// Computes the potential source ranges that can be skipped by the preprocessor
+/// when skipping a directive like #if, #ifdef or #elsif.
+///
+/// \returns false on success, true on error.
+bool computeSkippedRanges(ArrayRef<Token> Input,
+                          llvm::SmallVectorImpl<SkippedRange> &Range);
+
 } // end namespace minimize_source_to_dependency_directives
 
 /// Minimize the input down to the preprocessor directives that might have
diff --git a/clang/include/clang/Lex/Lexer.h b/clang/include/clang/Lex/Lexer.h
--- a/clang/include/clang/Lex/Lexer.h
+++ b/clang/include/clang/Lex/Lexer.h
@@ -265,6 +265,21 @@
   /// Return the current location in the buffer.
   const char *getBufferLocation() const { return BufferPtr; }
 
+  /// Returns the current lexing offset.
+  unsigned getCurrentBufferOffset() {
+    assert(BufferPtr >= BufferStart && "Invalid buffer state");
+    return BufferPtr - BufferStart;
+  }
+
+  /// Skip over \p NumBytes bytes.
+  ///
+  /// If the skip is successful, the next token will be lexed from the new
+  /// offset. The lexer also assumes that we skipped to the start of the line.
+  ///
+  /// \returns true if the skip failed (new offset would have been past the
+  /// end of the buffer), false otherwise.
+  bool skipOver(unsigned NumBytes);
+
   /// Stringify - Convert the specified string into a C string by i) escaping
   /// '\\' and " characters and ii) replacing newline character(s) with "\\n".
   /// If Charify is true, this escapes the ' character instead of ".
diff --git a/clang/include/clang/Lex/PPCallbacks.h b/clang/include/clang/Lex/PPCallbacks.h
--- a/clang/include/clang/Lex/PPCallbacks.h
+++ b/clang/include/clang/Lex/PPCallbacks.h
@@ -370,6 +370,12 @@
   /// \param IfLoc the source location of the \#if/\#ifdef/\#ifndef directive.
   virtual void Endif(SourceLocation Loc, SourceLocation IfLoc) {
   }
+
+  /// This skipped range class returns an optional thing.
+  virtual Optional<unsigned> getSkippedRangeForExcludedConditionalBlock(
+      Preprocessor &PP, SourceLocation HashLoc, unsigned CurLexerBufferOffset) {
+    return None;
+  }
 };
 
 /// Simple wrapper class for chaining callbacks.
@@ -606,6 +612,16 @@
     First->Endif(Loc, IfLoc);
     Second->Endif(Loc, IfLoc);
   }
+
+  Optional<unsigned> getSkippedRangeForExcludedConditionalBlock(
+      Preprocessor &PP, SourceLocation HashLoc,
+      unsigned CurLexerBufferOffset) override {
+    if (auto I = First->getSkippedRangeForExcludedConditionalBlock(
+            PP, HashLoc, CurLexerBufferOffset))
+      return I;
+    return Second->getSkippedRangeForExcludedConditionalBlock(
+        PP, HashLoc, CurLexerBufferOffset);
+  }
 };
 
 }  // end namespace clang
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningFilesystem.h
@@ -10,6 +10,7 @@
 #define LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_FILESYSTEM_H
 
 #include "clang/Basic/LLVM.h"
+#include "clang/Tooling/DependencyScanning/PPRangeSkipping.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/Support/Allocator.h"
@@ -76,6 +77,12 @@
     return MaybeStat->getName();
   }
 
+  /// Return the mapping between location -> distance that is used to speed up
+  /// the block skipping in the preprocessor.
+  const SkippedRangeMapping &getPPSkippedRangeMapping() const {
+    return PPSkippedRangeMapping;
+  }
+
   CachedFileSystemEntry(CachedFileSystemEntry &&) = default;
   CachedFileSystemEntry &operator=(CachedFileSystemEntry &&) = default;
 
@@ -89,6 +96,7 @@
   // Note: small size of 1 allows us to store an empty string with an implicit
   // null terminator without any allocations.
   llvm::SmallString<1> Contents;
+  SkippedRangeMapping PPSkippedRangeMapping;
 };
 
 /// This class is a shared cache, that caches the 'stat' and 'open' calls to the
@@ -133,8 +141,10 @@
 public:
   DependencyScanningWorkerFilesystem(
       DependencyScanningFilesystemSharedCache &SharedCache,
-      IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS)
-      : ProxyFileSystem(std::move(FS)), SharedCache(SharedCache) {}
+      IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS,
+      PreprocessorSkippedMappings &PPSkippedRanges)
+      : ProxyFileSystem(std::move(FS)), SharedCache(SharedCache),
+        PPSkippedRanges(PPSkippedRanges) {}
 
   llvm::ErrorOr<llvm::vfs::Status> status(const Twine &Path) override;
   llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
@@ -159,6 +169,7 @@
   /// The local cache is used by the worker thread to cache file system queries
   /// locally instead of querying the global cache every time.
   llvm::StringMap<const CachedFileSystemEntry *, llvm::BumpPtrAllocator> Cache;
+  PreprocessorSkippedMappings &PPSkippedRanges;
 };
 
 } // end namespace dependencies
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningService.h
@@ -34,12 +34,15 @@
 /// the invidual dependency scanning workers.
 class DependencyScanningService {
 public:
-  DependencyScanningService(ScanningMode Mode, bool ReuseFileManager = true);
+  DependencyScanningService(ScanningMode Mode, bool ReuseFileManager = true,
+                            bool SkipExcludedPPRanges = true);
 
   ScanningMode getMode() const { return Mode; }
 
   bool canReuseFileManager() const { return ReuseFileManager; }
 
+  bool canSkipExcludedPPRanges() const { return SkipExcludedPPRanges; }
+
   DependencyScanningFilesystemSharedCache &getSharedCache() {
     return SharedCache;
   }
@@ -47,6 +50,10 @@
 private:
   const ScanningMode Mode;
   const bool ReuseFileManager;
+  /// Set to true to use the preprocessor optimization that skips excluded PP
+  /// ranges by bumping the buffer pointer in the lexer instead of lexing the
+  /// tokens in the range until reaching the corresponding directive.
+  const bool SkipExcludedPPRanges;
   /// The global file system cache.
   DependencyScanningFilesystemSharedCache SharedCache;
 };
diff --git a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
--- a/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
+++ b/clang/include/clang/Tooling/DependencyScanning/DependencyScanningWorker.h
@@ -14,6 +14,7 @@
 #include "clang/Basic/LLVM.h"
 #include "clang/Frontend/PCHContainerOperations.h"
 #include "clang/Tooling/CompilationDatabase.h"
+#include "clang/Tooling/DependencyScanning/PPRangeSkipping.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileSystem.h"
 #include <string>
@@ -62,6 +63,10 @@
 private:
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts;
   std::shared_ptr<PCHContainerOperations> PCHContainerOps;
+  /// The mapping that holds the active 'skip' mappings that are used by a
+  /// particular preprocessor.
+  PreprocessorSkippedMappings PPSkippedRanges;
+  const bool SkipExcludedPPRanges;
 
   llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> RealFS;
   /// The file system that is used by each worker when scanning for
diff --git a/clang/include/clang/Tooling/DependencyScanning/PPRangeSkipping.h b/clang/include/clang/Tooling/DependencyScanning/PPRangeSkipping.h
new file mode 100644
--- /dev/null
+++ b/clang/include/clang/Tooling/DependencyScanning/PPRangeSkipping.h
@@ -0,0 +1,87 @@
+//===- PPRangeSkipping.h - PP Callbacks to skip inactive range --*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_PP_RANGE_SKIPPING_H
+#define LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_PP_RANGE_SKIPPING_H
+
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/PPCallbacks.h"
+#include "llvm/ADT/DenseMap.h"
+#include <string>
+
+namespace clang {
+namespace tooling {
+namespace dependencies {
+
+/// A mapping from an offset into a buffer to the number of bytes that can be
+/// skipped by the preprocessor when skipping over inactive preprocessor ranges.
+using SkippedRangeMapping = llvm::DenseMap<unsigned, unsigned>;
+
+/// Contains the currently active skipped range mappings for a particular
+/// preprocessor instance.
+class PreprocessorSkippedMappings {
+public:
+  /// Clears the buffer -> skipped range mappings.
+  void reset() { MappingForBuffer.clear(); }
+
+  /// Inserts a new mapping that maps from the specified memory buffer to the
+  /// specified skipped range mappings.
+  void setSkippedRanges(const llvm::MemoryBuffer *Buf,
+                        const SkippedRangeMapping *Mapping) {
+    MappingForBuffer[Buf] = Mapping;
+  }
+
+  /// Returns the skipped range mappings for the given buffer or null if none
+  /// exist.
+  const SkippedRangeMapping *
+  getSkippedRanges(const llvm::MemoryBuffer *Buf) const {
+    auto It = MappingForBuffer.find(Buf);
+    if (It != MappingForBuffer.end())
+      return It->getSecond();
+    return nullptr;
+  }
+
+private:
+  llvm::DenseMap<const llvm::MemoryBuffer *, const SkippedRangeMapping *>
+      MappingForBuffer;
+};
+
+/// A PP callbacks instance that implements fast PP skipping.
+class PPRangeSkippingCallbacks final : public PPCallbacks {
+public:
+  PPRangeSkippingCallbacks(PreprocessorSkippedMappings &BufferMappings)
+      : BufferMappings(BufferMappings) {}
+
+  Optional<unsigned> getSkippedRangeForExcludedConditionalBlock(
+      Preprocessor &PP, SourceLocation HashLoc,
+      unsigned CurLexerBufferOffset) override;
+
+  void FileChanged(SourceLocation Loc, FileChangeReason Reason,
+                   SrcMgr::CharacteristicKind FileType,
+                   FileID PrevFID) override;
+
+private:
+  PreprocessorSkippedMappings &BufferMappings;
+  struct FileInfo {
+    SourceLocation Loc;
+    FileID File;
+    const SkippedRangeMapping *PPSkippedRanges = nullptr;
+
+    FileInfo(SourceLocation Loc) : Loc(Loc) {}
+
+    bool isValid() const { return File.isValid(); }
+  };
+  llvm::SmallVector<FileInfo, 8> FileStack;
+};
+
+} // end namespace dependencies
+} // end namespace tooling
+} // end namespace clang
+
+#endif // LLVM_CLANG_TOOLING_DEPENDENCY_SCANNING_PP_RANGE_SKIPPING_H
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -75,6 +75,15 @@
   Invocation = std::move(Value);
 }
 
+void CompilerInstance::setAdditionalPPCallbacks(
+    std::unique_ptr<PPCallbacks> PPC) {
+  if (AdditionalPPCallbacks)
+    AdditionalPPCallbacks = std::make_unique<PPChainedCallbacks>(
+        std::move(AdditionalPPCallbacks), std::move(PPC));
+  else
+    AdditionalPPCallbacks = std::move(PPC);
+}
+
 bool CompilerInstance::shouldBuildGlobalModuleIndex() const {
   return (BuildGlobalModuleIndex ||
           (ModuleManager && ModuleManager->isGlobalIndexUnavailable() &&
@@ -457,6 +466,9 @@
                            /*ShowAllHeaders=*/true, /*OutputPath=*/"",
                            /*ShowDepth=*/true, /*MSStyle=*/true);
   }
+
+  if (AdditionalPPCallbacks)
+    PP->addPPCallbacks(std::move(AdditionalPPCallbacks));
 }
 
 std::string CompilerInstance::getSpecificModuleCachePath() {
diff --git a/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp b/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
--- a/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
+++ b/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
@@ -865,6 +865,54 @@
   return Error;
 }
 
+bool clang::minimize_source_to_dependency_directives::computeSkippedRanges(
+    ArrayRef<Token> Input, llvm::SmallVectorImpl<SkippedRange> &Range) {
+  struct Directive {
+    enum DirectiveKind {
+      If,  // if/ifdef/ifndef
+      Else // elif,else
+    };
+    int Offset;
+    DirectiveKind Kind;
+  };
+  llvm::SmallVector<Directive, 32> Offsets;
+  for (const Token &T : Input) {
+    switch (T.K) {
+    case pp_if:
+    case pp_ifdef:
+    case pp_ifndef:
+      Offsets.push_back({T.Offset, Directive::If});
+      break;
+
+    case pp_elif:
+    case pp_else: {
+      if (Offsets.empty())
+        return true;
+      int PreviousOffset = Offsets.back().Offset;
+      Range.push_back({PreviousOffset, T.Offset - PreviousOffset});
+      Offsets.push_back({T.Offset, Directive::Else});
+      break;
+    }
+
+    case pp_endif: {
+      if (Offsets.empty())
+        return true;
+      int PreviousOffset = Offsets.back().Offset;
+      Range.push_back({PreviousOffset, T.Offset - PreviousOffset});
+      do {
+        Directive::DirectiveKind Kind = Offsets.pop_back_val().Kind;
+        if (Kind == Directive::If)
+          break;
+      } while (!Offsets.empty());
+      break;
+    }
+    default:
+      break;
+    }
+  }
+  return false;
+}
+
 bool clang::minimizeSourceToDependencyDirectives(
     StringRef Input, SmallVectorImpl<char> &Output,
     SmallVectorImpl<Token> &Tokens, DiagnosticsEngine *Diags,
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -218,6 +218,15 @@
   return L;
 }
 
+bool Lexer::skipOver(unsigned NumBytes) {
+  IsAtPhysicalStartOfLine = true;
+  IsAtStartOfLine = true;
+  if ((BufferPtr + NumBytes) > BufferEnd)
+    return true;
+  BufferPtr += NumBytes;
+  return false;
+}
+
 template <typename T> static void StringifyImpl(T &Str, char Quote) {
   typename T::size_type i = 0, e = Str.size();
   while (i < e) {
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -396,6 +396,13 @@
   // disabling warnings, etc.
   CurPPLexer->LexingRawMode = true;
   Token Tok;
+  if (Callbacks && HashTokenLoc.isFileID()) {
+    if (auto SkipLength = Callbacks->getSkippedRangeForExcludedConditionalBlock(
+            *this, HashTokenLoc, CurLexer->getCurrentBufferOffset())) {
+      // Skip to the next '#endif' / '#else' / '#elif'.
+      CurLexer->skipOver(*SkipLength);
+    }
+  }
   while (true) {
     CurLexer->Lex(Tok);
 
diff --git a/clang/lib/Tooling/DependencyScanning/CMakeLists.txt b/clang/lib/Tooling/DependencyScanning/CMakeLists.txt
--- a/clang/lib/Tooling/DependencyScanning/CMakeLists.txt
+++ b/clang/lib/Tooling/DependencyScanning/CMakeLists.txt
@@ -7,6 +7,7 @@
   DependencyScanningFilesystem.cpp
   DependencyScanningService.cpp
   DependencyScanningWorker.cpp
+  PPRangeSkipping.cpp
 
   DEPENDS
   ClangDriverOptions
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -69,6 +69,25 @@
   // Now make the null terminator implicit again, so that Clang's lexer can find
   // it right where the buffer ends.
   Result.Contents.pop_back();
+
+  // Compute the skipped PP ranges that speedup skipping over inactive
+  // preprocessor blocks.
+  llvm::SmallVector<minimize_source_to_dependency_directives::SkippedRange, 32>
+      SkippedRanges;
+  minimize_source_to_dependency_directives::computeSkippedRanges(Tokens,
+                                                                 SkippedRanges);
+  SkippedRangeMapping Mapping;
+  for (const auto &Range : SkippedRanges) {
+    if (Range.Length < 16) {
+      // Ignore small ranges as non-profitable.
+      // FIXME: This is a heuristic, its worth investigating the tradeoffs
+      // when it should be applied.
+      continue;
+    }
+    Mapping[Range.Offset] = Range.Length;
+  }
+  Result.PPSkippedRangeMapping = std::move(Mapping);
+
   return Result;
 }
 
@@ -172,14 +191,19 @@
 };
 
 llvm::ErrorOr<std::unique_ptr<llvm::vfs::File>>
-createFile(const CachedFileSystemEntry *Entry) {
+createFile(const CachedFileSystemEntry *Entry,
+           PreprocessorSkippedMappings &PPSkippedRanges) {
   llvm::ErrorOr<StringRef> Contents = Entry->getContents();
   if (!Contents)
     return Contents.getError();
-  return std::make_unique<MinimizedVFSFile>(
+  auto Result = std::make_unique<MinimizedVFSFile>(
       llvm::MemoryBuffer::getMemBuffer(*Contents, Entry->getName(),
                                        /*RequiresNullTerminator=*/false),
       *Entry->getStatus());
+  if (!Entry->getPPSkippedRangeMapping().empty())
+    PPSkippedRanges.setSkippedRanges(Result->getBufferPtr(),
+                                     &Entry->getPPSkippedRangeMapping());
+  return Result;
 }
 
 } // end anonymous namespace
@@ -191,7 +215,7 @@
 
   // Check the local cache first.
   if (const CachedFileSystemEntry *Entry = getCachedEntry(Filename))
-    return createFile(Entry);
+    return createFile(Entry, PPSkippedRanges);
 
   // FIXME: Handle PCM/PCH files.
   // FIXME: Handle module map files.
@@ -214,5 +238,5 @@
 
   // Store the result in the local cache.
   setCachedEntry(Filename, Result);
-  return createFile(Result);
+  return createFile(Result, PPSkippedRanges);
 }
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp
@@ -13,5 +13,7 @@
 using namespace dependencies;
 
 DependencyScanningService::DependencyScanningService(ScanningMode Mode,
-                                                     bool ReuseFileManager)
-    : Mode(Mode), ReuseFileManager(ReuseFileManager) {}
+                                                     bool ReuseFileManager,
+                                                     bool SkipExcludedPPRanges)
+    : Mode(Mode), ReuseFileManager(ReuseFileManager),
+      SkipExcludedPPRanges(SkipExcludedPPRanges) {}
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningWorker.cpp
@@ -66,9 +66,10 @@
 public:
   DependencyScanningAction(
       StringRef WorkingDirectory, DependencyConsumer &Consumer,
-      llvm::IntrusiveRefCntPtr<DependencyScanningWorkerFilesystem> DepFS)
+      llvm::IntrusiveRefCntPtr<DependencyScanningWorkerFilesystem> DepFS,
+      PreprocessorSkippedMappings *PPSkippedRanges)
       : WorkingDirectory(WorkingDirectory), Consumer(Consumer),
-        DepFS(std::move(DepFS)) {}
+        DepFS(std::move(DepFS)), PPSkippedRanges(PPSkippedRanges) {}
 
   bool runInvocation(std::shared_ptr<CompilerInvocation> Invocation,
                      FileManager *FileMgr,
@@ -107,6 +108,14 @@
     Compiler.setFileManager(FileMgr);
     Compiler.createSourceManager(*FileMgr);
 
+    // Set the PP Callbacks which should speed up excluded conditional block
+    // skipping in the preprocessor.
+    if (PPSkippedRanges) {
+      PPSkippedRanges->reset();
+      Compiler.setAdditionalPPCallbacks(
+          std::make_unique<PPRangeSkippingCallbacks>(*PPSkippedRanges));
+    }
+
     // Create the dependency collector that will collect the produced
     // dependencies.
     //
@@ -134,18 +143,20 @@
   StringRef WorkingDirectory;
   DependencyConsumer &Consumer;
   llvm::IntrusiveRefCntPtr<DependencyScanningWorkerFilesystem> DepFS;
+  PreprocessorSkippedMappings *PPSkippedRanges;
 };
 
 } // end anonymous namespace
 
 DependencyScanningWorker::DependencyScanningWorker(
-    DependencyScanningService &Service) {
+    DependencyScanningService &Service)
+    : SkipExcludedPPRanges(Service.canSkipExcludedPPRanges()) {
   DiagOpts = new DiagnosticOptions();
   PCHContainerOps = std::make_shared<PCHContainerOperations>();
   RealFS = new ProxyFileSystemWithoutChdir(llvm::vfs::getRealFileSystem());
   if (Service.getMode() == ScanningMode::MinimizedSourcePreprocessing)
     DepFS = new DependencyScanningWorkerFilesystem(Service.getSharedCache(),
-                                                   RealFS);
+                                                   RealFS, PPSkippedRanges);
   if (Service.canReuseFileManager())
     Files = new FileManager(FileSystemOptions(), RealFS);
 }
@@ -178,7 +189,9 @@
     Tool.setRestoreWorkingDir(false);
     Tool.setPrintErrorMessage(false);
     Tool.setDiagnosticConsumer(&DC);
-    DependencyScanningAction Action(WorkingDirectory, Consumer, DepFS);
+    DependencyScanningAction Action(WorkingDirectory, Consumer, DepFS,
+                                    SkipExcludedPPRanges ? &PPSkippedRanges
+                                                         : nullptr);
     return !Tool.run(&Action);
   });
 }
diff --git a/clang/lib/Tooling/DependencyScanning/PPRangeSkipping.cpp b/clang/lib/Tooling/DependencyScanning/PPRangeSkipping.cpp
new file mode 100644
--- /dev/null
+++ b/clang/lib/Tooling/DependencyScanning/PPRangeSkipping.cpp
@@ -0,0 +1,71 @@
+//===- PPRangeSkipping.cpp - PP Callbacks to skip inactive range ----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Tooling/DependencyScanning/PPRangeSkipping.h"
+#include "clang/Lex/Preprocessor.h"
+
+using namespace clang;
+using namespace tooling;
+using namespace dependencies;
+
+Optional<unsigned>
+PPRangeSkippingCallbacks::getSkippedRangeForExcludedConditionalBlock(
+    Preprocessor &PP, SourceLocation HashLoc, unsigned CurLexerBufferOffset) {
+  if (FileStack.empty())
+    return None;
+  const SourceManager &SM = PP.getSourceManager();
+
+  // Retrieve the information about the file we're currently lexing.
+  auto &Info = FileStack.back();
+  if (!Info.isValid()) {
+    std::pair<FileID, unsigned> F = SM.getDecomposedLoc(Info.Loc);
+    Info.File = F.first;
+    const auto *Buf = SM.getBuffer(F.first);
+    if (const auto *PPSkippedRanges = BufferMappings.getSkippedRanges(Buf)) {
+      Info.PPSkippedRanges = PPSkippedRanges;
+    }
+  }
+
+  if (!Info.PPSkippedRanges)
+    return None;
+
+  auto HashFileOffset = SM.getDecomposedLoc(HashLoc);
+  if (HashFileOffset.first != Info.File)
+    return None;
+  // Check if the offset of '#' is mapped in the skipped ranges.
+  auto It = Info.PPSkippedRanges->find(HashFileOffset.second);
+  if (It == Info.PPSkippedRanges->end()) {
+    return None;
+  }
+  unsigned BytesToSkip = It->getSecond();
+  assert(CurLexerBufferOffset >= HashFileOffset.second &&
+         "lexer is before the hash?");
+  // Take into account the fact that the lexer has already advanced, so the
+  // number of bytes to skip must be adjusted.
+  unsigned LengthDiff = CurLexerBufferOffset - HashFileOffset.second;
+  assert(BytesToSkip >= LengthDiff && "lexer is after the skipped range?");
+  return BytesToSkip - LengthDiff;
+}
+
+void PPRangeSkippingCallbacks::FileChanged(SourceLocation Loc,
+                                           FileChangeReason Reason,
+                                           SrcMgr::CharacteristicKind FileType,
+                                           FileID PrevFID) {
+  switch (Reason) {
+  case EnterFile:
+    if (Loc.isValid())
+      FileStack.push_back(Loc);
+    break;
+  case ExitFile:
+    if (!FileStack.empty())
+      FileStack.pop_back();
+    break;
+  default:
+    break;
+  }
+}
diff --git a/clang/test/ClangScanDeps/regular_cdb.cpp b/clang/test/ClangScanDeps/regular_cdb.cpp
--- a/clang/test/ClangScanDeps/regular_cdb.cpp
+++ b/clang/test/ClangScanDeps/regular_cdb.cpp
@@ -12,6 +12,8 @@
 // RUN:   FileCheck --check-prefixes=CHECK1,CHECK2,CHECK2NO %s
 // RUN: clang-scan-deps -compilation-database %t.cdb -j 1 -mode preprocess | \
 // RUN:   FileCheck --check-prefixes=CHECK1,CHECK2,CHECK2NO %s
+// RUN: clang-scan-deps -compilation-database %t.cdb -j 1 -mode preprocess-minimized-sources \
+// RUN:   -skip-excluded-pp-ranges=0 | FileCheck --check-prefixes=CHECK1,CHECK2,CHECK2NO %s
 //
 // Make sure we didn't produce any dependency files!
 // RUN: not cat %t.dir/regular_cdb.d
diff --git a/clang/tools/clang-scan-deps/ClangScanDeps.cpp b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
--- a/clang/tools/clang-scan-deps/ClangScanDeps.cpp
+++ b/clang/tools/clang-scan-deps/ClangScanDeps.cpp
@@ -168,6 +168,14 @@
     llvm::cl::desc("Reuse the file manager and its cache between invocations."),
     llvm::cl::init(true), llvm::cl::cat(DependencyScannerCategory));
 
+llvm::cl::opt<bool> SkipExcludedPPRanges(
+    "skip-excluded-pp-ranges",
+    llvm::cl::desc(
+        "Use the preprocessor optimization that skips excluded conditionals by "
+        "bumping the buffer pointer in the lexer instead of lexing the tokens  "
+        "until reaching the end directive."),
+    llvm::cl::init(true), llvm::cl::cat(DependencyScannerCategory));
+
 } // end anonymous namespace
 
 int main(int argc, const char **argv) {
@@ -214,7 +222,8 @@
   // Print out the dependency results to STDOUT by default.
   SharedStream DependencyOS(llvm::outs());
 
-  DependencyScanningService Service(ScanMode, ReuseFileManager);
+  DependencyScanningService Service(ScanMode, ReuseFileManager,
+                                    SkipExcludedPPRanges);
 #if LLVM_ENABLE_THREADS
   unsigned NumWorkers =
       NumThreads == 0 ? llvm::hardware_concurrency() : NumThreads;
diff --git a/clang/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp b/clang/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp
--- a/clang/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp
+++ b/clang/unittests/Lex/DependencyDirectivesSourceMinimizerTest.cpp
@@ -617,4 +617,46 @@
             minimize_source_to_dependency_directives::cxx_module_decl);
 }
 
+TEST(MinimizeSourceToDependencyDirectivesTest, SkippedPPRangesBasic) {
+  SmallString<128> Out;
+  SmallVector<Token, 32> Toks;
+  StringRef Source = "#ifndef GUARD\n"
+                     "#define GUARD\n"
+                     "void foo();\n"
+                     "#endif\n";
+  ASSERT_FALSE(minimizeSourceToDependencyDirectives(Source, Out, Toks));
+  SmallVector<SkippedRange, 4> Ranges;
+  ASSERT_FALSE(computeSkippedRanges(Toks, Ranges));
+  EXPECT_EQ(Ranges.size(), 1u);
+  EXPECT_EQ(Ranges[0].Offset, 0);
+  EXPECT_EQ(Ranges[0].Length, (int)Out.find("#endif"));
+}
+
+TEST(MinimizeSourceToDependencyDirectivesTest, SkippedPPRangesNested) {
+  SmallString<128> Out;
+  SmallVector<Token, 32> Toks;
+  StringRef Source = "#ifndef GUARD\n"
+                     "#define GUARD\n"
+                     "#if FOO\n"
+                     "#include hello\n"
+                     "#elif BAR\n"
+                     "#include bye\n"
+                     "#endif\n"
+                     "#else\n"
+                     "#include nothing\n"
+                     "#endif\n";
+  ASSERT_FALSE(minimizeSourceToDependencyDirectives(Source, Out, Toks));
+  SmallVector<SkippedRange, 4> Ranges;
+  ASSERT_FALSE(computeSkippedRanges(Toks, Ranges));
+  EXPECT_EQ(Ranges.size(), 4u);
+  EXPECT_EQ(Ranges[0].Offset, (int)Out.find("#if FOO"));
+  EXPECT_EQ(Ranges[0].Offset + Ranges[0].Length, (int)Out.find("#elif"));
+  EXPECT_EQ(Ranges[1].Offset, (int)Out.find("#elif BAR"));
+  EXPECT_EQ(Ranges[1].Offset + Ranges[1].Length, (int)Out.find("#endif"));
+  EXPECT_EQ(Ranges[2].Offset, 0);
+  EXPECT_EQ(Ranges[2].Length, (int)Out.find("#else"));
+  EXPECT_EQ(Ranges[3].Offset, (int)Out.find("#else"));
+  EXPECT_EQ(Ranges[3].Offset + Ranges[3].Length, (int)Out.rfind("#endif"));
+}
+
 } // end anonymous namespace