From: Sven Over <over@fb.com>
Date: Fri, 1 Apr 2016 15:31:10 +0000 (-0700)
Subject: folly: replace old-style header guards with "pragma once"
X-Git-Tag: 2016.07.26~384
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=dee8a5180aa542d98d1b71c74f83a006e4627952;p=folly.git

folly: replace old-style header guards with "pragma once"

Summary:Most header files in folly already used "#pragma once" to
protect against multiple inclusion. This diff removes old-style
ifndef/define/endif header guards and replaces them with
pragma once.

In some cases the defined symbol is tested in other header
files. In those cases the "#define" is kept.

Reviewed By: igorsugak

Differential Revision: D3054492

fb-gh-sync-id: 20aa0b9b926a30dd021e4b8f5440e8888874681c
fbshipit-source-id: 20aa0b9b926a30dd021e4b8f5440e8888874681c
---

diff --git a/folly/Arena.h b/folly/Arena.h
index daea8bc1..8b928b03 100644
--- a/folly/Arena.h
+++ b/folly/Arena.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_ARENA_H_
+#pragma once
 #define FOLLY_ARENA_H_
 
 #include <cassert>
@@ -243,5 +243,3 @@ struct IsArenaAllocator<SysArena> : std::true_type { };
 }  // namespace folly
 
 #include <folly/Arena-inl.h>
-
-#endif /* FOLLY_ARENA_H_ */
diff --git a/folly/Assume.h b/folly/Assume.h
index ca37c145..7c50a679 100644
--- a/folly/Assume.h
+++ b/folly/Assume.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BASE_ASSUME_H_
-#define FOLLY_BASE_ASSUME_H_
+#pragma once
 
 #include <folly/Portability.h>
 #include <glog/logging.h>
@@ -45,5 +44,3 @@ FOLLY_ALWAYS_INLINE void assume(bool cond) {
 }
 
 }  // namespace folly
-
-#endif
diff --git a/folly/AtomicBitSet.h b/folly/AtomicBitSet.h
index 3d02d572..caa61e5a 100644
--- a/folly/AtomicBitSet.h
+++ b/folly/AtomicBitSet.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_ATOMICBITSET_H_
-#define FOLLY_ATOMICBITSET_H_
+#pragma once
 
 #include <array>
 #include <atomic>
@@ -158,5 +157,3 @@ inline bool AtomicBitSet<N>::operator[](size_t idx) const {
 }
 
 }  // namespaces
-
-#endif /* FOLLY_ATOMICBITSET_H_ */
diff --git a/folly/AtomicHashArray.h b/folly/AtomicHashArray.h
index a66b4902..3269a01e 100644
--- a/folly/AtomicHashArray.h
+++ b/folly/AtomicHashArray.h
@@ -29,7 +29,7 @@
  *  @author Jordan DeLong <delong.j@fb.com>
  */
 
-#ifndef FOLLY_ATOMICHASHARRAY_H_
+#pragma once
 #define FOLLY_ATOMICHASHARRAY_H_
 
 #include <atomic>
@@ -429,5 +429,3 @@ friend class AtomicHashMap<KeyT,
 } // namespace folly
 
 #include <folly/AtomicHashArray-inl.h>
-
-#endif // FOLLY_ATOMICHASHARRAY_H_
diff --git a/folly/AtomicHashMap.h b/folly/AtomicHashMap.h
index 53c8d8af..b4a0563e 100644
--- a/folly/AtomicHashMap.h
+++ b/folly/AtomicHashMap.h
@@ -79,7 +79,7 @@
  *
  */
 
-#ifndef FOLLY_ATOMICHASHMAP_H_
+#pragma once
 #define FOLLY_ATOMICHASHMAP_H_
 
 #include <boost/iterator/iterator_facade.hpp>
@@ -472,5 +472,3 @@ using QuadraticProbingAtomicHashMap =
 } // namespace folly
 
 #include <folly/AtomicHashMap-inl.h>
-
-#endif // FOLLY_ATOMICHASHMAP_H_
diff --git a/folly/AtomicLinkedList.h b/folly/AtomicLinkedList.h
index cf880c58..459036ef 100644
--- a/folly/AtomicLinkedList.h
+++ b/folly/AtomicLinkedList.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_ATOMIC_LINKED_LIST_H_
-#define FOLLY_ATOMIC_LINKED_LIST_H_
+#pragma once
 
 #include <atomic>
 #include <cassert>
@@ -134,5 +133,3 @@ class AtomicLinkedList {
 };
 
 } // namespace folly
-
-#endif
diff --git a/folly/AtomicStruct.h b/folly/AtomicStruct.h
index d478b90c..0587b964 100644
--- a/folly/AtomicStruct.h
+++ b/folly/AtomicStruct.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_ATOMIC_STRUCT_H_
-#define FOLLY_ATOMIC_STRUCT_H_
+#pragma once
 
 #include <atomic>
 #include <type_traits>
@@ -135,5 +134,3 @@ template <> struct AtomicStructIntPick<8> { typedef uint64_t type; };
 } // namespace detail
 
 } // namespace folly
-
-#endif
diff --git a/folly/AtomicUnorderedMap.h b/folly/AtomicUnorderedMap.h
index eb361144..68fc585d 100644
--- a/folly/AtomicUnorderedMap.h
+++ b/folly/AtomicUnorderedMap.h
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#ifndef FOLLY_ATOMICUNORDEREDMAP_H
-#define FOLLY_ATOMICUNORDEREDMAP_H
+
+#pragma once
 
 #include <atomic>
 #include <functional>
@@ -519,4 +519,3 @@ struct MutableData {
 
 
 }
-#endif
diff --git a/folly/Baton.h b/folly/Baton.h
index c14e57f3..c10f7146 100644
--- a/folly/Baton.h
+++ b/folly/Baton.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BATON_H
-#define FOLLY_BATON_H
+#pragma once
 
 #include <stdint.h>
 #include <atomic>
@@ -297,5 +296,3 @@ struct Baton {
 };
 
 } // namespace folly
-
-#endif
diff --git a/folly/Benchmark.h b/folly/Benchmark.h
index 7ca0b748..0a384b40 100644
--- a/folly/Benchmark.h
+++ b/folly/Benchmark.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BENCHMARK_H_
-#define FOLLY_BENCHMARK_H_
+#pragma once
 
 #include <folly/Portability.h>
 #include <folly/Preprocessor.h> // for FB_ANONYMOUS_VARIABLE
@@ -536,5 +535,3 @@ void doNotOptimizeAway(T&& datum) {
   if (auto FB_ANONYMOUS_VARIABLE(BENCHMARK_SUSPEND) =   \
       ::folly::BenchmarkSuspender()) {}                 \
   else
-
-#endif // FOLLY_BENCHMARK_H_
diff --git a/folly/Bits.h b/folly/Bits.h
index 61a7407d..9d91aefa 100644
--- a/folly/Bits.h
+++ b/folly/Bits.h
@@ -52,8 +52,7 @@
  * @author Tudor Bosman (tudorb@fb.com)
  */
 
-#ifndef FOLLY_BITS_H_
-#define FOLLY_BITS_H_
+#pragma once
 
 #if !defined(__clang__) && !(defined(_MSC_VER) && (_MSC_VER < 1900))
 #define FOLLY_INTRINSIC_CONSTEXPR constexpr
@@ -574,5 +573,3 @@ inline void storeUnaligned(void* p, T value) {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_BITS_H_ */
diff --git a/folly/CPortability.h b/folly/CPortability.h
index 6f35319d..febf2a14 100644
--- a/folly/CPortability.h
+++ b/folly/CPortability.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef CPORTABILITY_H
-#define CPORTABILITY_H
+#pragma once
 
 /* These definitions are in a separate file so that they
  * may be included from C- as well as C++-based projects. */
@@ -72,5 +71,3 @@
 #else
 # define UBSAN_DISABLE(x)
 #endif // UNDEFINED_SANITIZER
-
-#endif // CPORTABILITY_H
diff --git a/folly/Checksum.h b/folly/Checksum.h
index 1168badf..12028933 100644
--- a/folly/Checksum.h
+++ b/folly/Checksum.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_CHECKSUM_H_
-#define FOLLY_CHECKSUM_H_
+#pragma once
 
 #include <stdint.h>
 #include <cstddef>
@@ -39,5 +38,3 @@ uint32_t crc32c(const uint8_t* data, size_t nbytes,
     uint32_t startingChecksum = ~0U);
 
 } // folly
-
-#endif /* FOLLY_CHECKSUM_H_ */
diff --git a/folly/ConcurrentSkipList-inl.h b/folly/ConcurrentSkipList-inl.h
index 8fd13b63..e4144bcb 100644
--- a/folly/ConcurrentSkipList-inl.h
+++ b/folly/ConcurrentSkipList-inl.h
@@ -16,8 +16,7 @@
 
 // @author: Xin Liu <xliux@fb.com>
 
-#ifndef FOLLY_CONCURRENTSKIPLIST_INL_H_
-#define FOLLY_CONCURRENTSKIPLIST_INL_H_
+#pragma once
 
 #include <algorithm>
 #include <atomic>
@@ -333,5 +332,3 @@ class NodeRecycler<NodeType, NodeAlloc, typename std::enable_if<
 };
 
 }}  // namespaces
-
-#endif  // FOLLY_CONCURRENTSKIPLIST_INL_H_
diff --git a/folly/ConcurrentSkipList.h b/folly/ConcurrentSkipList.h
index 3ebdeb94..ff84de41 100644
--- a/folly/ConcurrentSkipList.h
+++ b/folly/ConcurrentSkipList.h
@@ -117,8 +117,7 @@ Sample usage:
      }
 */
 
-#ifndef FOLLY_CONCURRENT_SKIP_LIST_H_
-#define FOLLY_CONCURRENT_SKIP_LIST_H_
+#pragma once
 
 #include <algorithm>
 #include <atomic>
@@ -800,5 +799,3 @@ class ConcurrentSkipList<T, Comp, NodeAlloc, MAX_HEIGHT>::Skipper {
 };
 
 } // namespace folly
-
-#endif  // FOLLY_CONCURRENT_SKIP_LIST_H_
diff --git a/folly/ContainerTraits.h b/folly/ContainerTraits.h
index c83f4600..4d6d0814 100644
--- a/folly/ContainerTraits.h
+++ b/folly/ContainerTraits.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BASE_CONTAINER_TRAITS_H_
-#define FOLLY_BASE_CONTAINER_TRAITS_H_
+#pragma once
 
 #include <folly/Traits.h>
 
@@ -41,5 +40,3 @@ container_emplace_back_or_push_back(Container& container, Args&&... args) {
 }
 
 }
-
-#endif
diff --git a/folly/Conv.h b/folly/Conv.h
index d13ebcb2..eeeb3847 100644
--- a/folly/Conv.h
+++ b/folly/Conv.h
@@ -21,8 +21,7 @@
  * @author Andrei Alexandrescu (andrei.alexandrescu@fb.com)
  */
 
-#ifndef FOLLY_BASE_CONV_H_
-#define FOLLY_BASE_CONV_H_
+#pragma once
 
 #include <folly/FBString.h>
 #include <folly/Likely.h>
@@ -1287,5 +1286,3 @@ to(const Src & value) {
 #undef FOLLY_RANGE_CHECK_STRINGIZE
 #undef FOLLY_RANGE_CHECK_STRINGIZE2
 #endif
-
-#endif /* FOLLY_BASE_CONV_H_ */
diff --git a/folly/CppAttributes.h b/folly/CppAttributes.h
index 27bf267b..6bd6cfe3 100644
--- a/folly/CppAttributes.h
+++ b/folly/CppAttributes.h
@@ -20,8 +20,7 @@
  * @author Dominik Gabi
  */
 
-#ifndef FOLLY_BASE_ATTRIBUTES_H_
-#define FOLLY_BASE_ATTRIBUTES_H_
+#pragma once
 
 #ifndef __has_cpp_attribute
 #define FOLLY_HAS_CPP_ATTRIBUTE(x) 0
@@ -76,5 +75,3 @@
 #else
 #define FOLLY_NULLABLE
 #endif
-
-#endif /* FOLLY_BASE_ATTRIBUTES_H_ */
diff --git a/folly/CpuId.h b/folly/CpuId.h
index 096fc8d1..fe3d58bb 100644
--- a/folly/CpuId.h
+++ b/folly/CpuId.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_CPUID_H_
-#define FOLLY_CPUID_H_
+#pragma once
 
 #include <cstdint>
 #include <folly/Portability.h>
@@ -196,5 +195,3 @@ class CpuId {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_CPUID_H_ */
diff --git a/folly/DiscriminatedPtr.h b/folly/DiscriminatedPtr.h
index 2f76a658..24494eff 100644
--- a/folly/DiscriminatedPtr.h
+++ b/folly/DiscriminatedPtr.h
@@ -24,8 +24,7 @@
  * @author Tudor Bosman (tudorb@fb.com)
  */
 
-#ifndef FOLLY_DISCRIMINATEDPTR_H_
-#define FOLLY_DISCRIMINATEDPTR_H_
+#pragma once
 
 #include <limits>
 #include <stdexcept>
@@ -217,5 +216,3 @@ class DiscriminatedPtr {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_DISCRIMINATEDPTR_H_ */
diff --git a/folly/DynamicConverter.h b/folly/DynamicConverter.h
index 48bd7115..591f55a7 100644
--- a/folly/DynamicConverter.h
+++ b/folly/DynamicConverter.h
@@ -16,8 +16,7 @@
 
 // @author Nicholas Ormrod <njormrod@fb.com>
 
-#ifndef DYNAMIC_CONVERTER_H
-#define DYNAMIC_CONVERTER_H
+#pragma once
 
 #include <folly/dynamic.h>
 namespace folly {
@@ -354,5 +353,3 @@ dynamic toDynamic(const T& x) {
 }
 
 } // namespace folly
-
-#endif // DYNAMIC_CONVERTER_H
diff --git a/folly/EvictingCacheMap.h b/folly/EvictingCacheMap.h
index 58073840..3059fb5e 100644
--- a/folly/EvictingCacheMap.h
+++ b/folly/EvictingCacheMap.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EVICTINGHASHMAP_H_
-#define FOLLY_EVICTINGHASHMAP_H_
+#pragma once
 
 #include <algorithm>
 #include <exception>
@@ -492,5 +491,3 @@ class EvictingCacheMap : private boost::noncopyable {
 };
 
 } // folly
-
-#endif /* FOLLY_EVICTINGHASHMAP_H_ */
diff --git a/folly/Exception.h b/folly/Exception.h
index 30444b2b..85bbeda4 100644
--- a/folly/Exception.h
+++ b/folly/Exception.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXCEPTION_H_
-#define FOLLY_EXCEPTION_H_
+#pragma once
 
 #include <errno.h>
 
@@ -119,5 +118,3 @@ void throwOnFail(V&& value, Args&&... args) {
   ::folly::throwOnFail<E>((cond), "Check failed: " #cond)
 
 }  // namespace folly
-
-#endif /* FOLLY_EXCEPTION_H_ */
diff --git a/folly/ExceptionWrapper.h b/folly/ExceptionWrapper.h
index 39eceda4..22857a0b 100644
--- a/folly/ExceptionWrapper.h
+++ b/folly/ExceptionWrapper.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXCEPTIONWRAPPER_H
-#define FOLLY_EXCEPTIONWRAPPER_H
+#pragma once
 
 #include <cassert>
 #include <exception>
@@ -468,4 +467,3 @@ class try_and_catch<> : public exception_wrapper {
   }
 };
 }
-#endif
diff --git a/folly/FBString.h b/folly/FBString.h
index 2f025154..81f146dd 100644
--- a/folly/FBString.h
+++ b/folly/FBString.h
@@ -17,8 +17,7 @@
 // @author: Andrei Alexandrescu (aalexandre)
 // String type.
 
-#ifndef FOLLY_BASE_FBSTRING_H_
-#define FOLLY_BASE_FBSTRING_H_
+#pragma once
 
 #include <atomic>
 #include <limits>
@@ -2492,5 +2491,3 @@ FOLLY_FBSTRING_HASH
 #undef NDEBUG
 #undef FOLLY_DEFINED_NDEBUG_FOR_FBSTRING
 #endif // FOLLY_DEFINED_NDEBUG_FOR_FBSTRING
-
-#endif // FOLLY_BASE_FBSTRING_H_
diff --git a/folly/FBVector.h b/folly/FBVector.h
index c44defef..e1809f31 100644
--- a/folly/FBVector.h
+++ b/folly/FBVector.h
@@ -22,8 +22,7 @@
  * optimizations for use with relocatable types and jemalloc.
  */
 
-#ifndef FOLLY_FBVECTOR_H
-#define FOLLY_FBVECTOR_H
+#pragma once
 
 //=============================================================================
 // headers
@@ -1659,5 +1658,3 @@ void attach(fbvector<T, A>& v, T* data, size_t sz, size_t cap) {
 }
 
 } // namespace folly
-
-#endif // FOLLY_FBVECTOR_H
diff --git a/folly/File.h b/folly/File.h
index 53e58def..09a3b6bf 100644
--- a/folly/File.h
+++ b/folly/File.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FILE_H_
-#define FOLLY_FILE_H_
+#pragma once
 
 #include <fcntl.h>
 #include <sys/stat.h>
@@ -136,5 +135,3 @@ void swap(File& a, File& b);
 
 
 }  // namespace folly
-
-#endif /* FOLLY_FILE_H_ */
diff --git a/folly/FileUtil.h b/folly/FileUtil.h
index 31d368b0..a28b0477 100644
--- a/folly/FileUtil.h
+++ b/folly/FileUtil.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FILEUTIL_H_
-#define FOLLY_FILEUTIL_H_
+#pragma once
 
 #include <folly/Conv.h>
 #include <folly/Portability.h>
@@ -193,5 +192,3 @@ bool writeFile(const Container& data, const char* filename,
 }
 
 }  // namespaces
-
-#endif /* FOLLY_FILEUTIL_H_ */
diff --git a/folly/Fingerprint.h b/folly/Fingerprint.h
index c4f6978d..f1980ae2 100644
--- a/folly/Fingerprint.h
+++ b/folly/Fingerprint.h
@@ -42,8 +42,7 @@
  * @author Tudor Bosman (tudorb@facebook.com)
  */
 
-#ifndef FOLLY_FINGERPRINT_H_
-#define FOLLY_FINGERPRINT_H_
+#pragma once
 
 #include <cstdint>
 
@@ -261,5 +260,3 @@ inline uint64_t Fingerprint<128>::shlor64(uint64_t v) {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_FINGERPRINT_H_ */
diff --git a/folly/Foreach.h b/folly/Foreach.h
index c6e45835..d362c0ba 100644
--- a/folly/Foreach.h
+++ b/folly/Foreach.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BASE_FOREACH_H_
-#define FOLLY_BASE_FOREACH_H_
+#pragma once
 
 /*
  * Iterim macros (until we have C++0x range-based for) that simplify
@@ -227,5 +226,3 @@ downTo(T& iter, const U& begin) {
  */
 #define FOR_EACH_RANGE_R(i, begin, end) \
   for (auto i = (false ? (begin) : (end)); ::folly::detail::downTo(i, (begin));)
-
-#endif
diff --git a/folly/Format.h b/folly/Format.h
index 89332a1b..c34f3339 100644
--- a/folly/Format.h
+++ b/folly/Format.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FORMAT_H_
+#pragma once
 #define FOLLY_FORMAT_H_
 
 #include <cstdio>
@@ -433,5 +433,3 @@ vformatChecked(Str* out, StringPiece fmt, Container&& container) {
 #include <folly/Format-inl.h>
 
 #pragma GCC diagnostic pop
-
-#endif /* FOLLY_FORMAT_H_ */
diff --git a/folly/FormatArg.h b/folly/FormatArg.h
index 127745c4..6f25299e 100644
--- a/folly/FormatArg.h
+++ b/folly/FormatArg.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FORMATARG_H_
-#define FOLLY_FORMATARG_H_
+#pragma once
 
 #include <stdexcept>
 #include <folly/Conv.h>
@@ -275,5 +274,3 @@ inline int FormatArg::splitIntKey() {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_FORMATARG_H_ */
diff --git a/folly/FormatTraits.h b/folly/FormatTraits.h
index 9ff17bd6..54175da4 100644
--- a/folly/FormatTraits.h
+++ b/folly/FormatTraits.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FORMAT_TRAITS_H_
-#define FOLLY_FORMAT_TRAITS_H_
+#pragma once
 
 #include <type_traits>
 
@@ -62,5 +61,3 @@ struct IndexableTraitsAssoc : public FormatTraitsBase {
 };
 
 }}  // namespaces
-
-#endif /* FOLLY_FORMAT_TRAITS_H_ */
diff --git a/folly/GroupVarint.h b/folly/GroupVarint.h
index 136a7b17..f91191ce 100644
--- a/folly/GroupVarint.h
+++ b/folly/GroupVarint.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GROUPVARINT_H_
-#define FOLLY_GROUPVARINT_H_
+#pragma once
 
 #if !defined(__GNUC__) && !defined(_MSC_VER)
 #error GroupVarint.h requires GCC or MSVC
@@ -618,4 +617,3 @@ typedef GroupVarintDecoder<uint64_t> GroupVarint64Decoder;
 }  // namespace folly
 
 #endif /* FOLLY_X64 || defined(__i386__) || FOLLY_PPC64 */
-#endif /* FOLLY_GROUPVARINT_H_ */
diff --git a/folly/Hash.h b/folly/Hash.h
index 77f01a96..dd61fb76 100644
--- a/folly/Hash.h
+++ b/folly/Hash.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BASE_HASH_H_
-#define FOLLY_BASE_HASH_H_
+#pragma once
 
 #include <cstdint>
 #include <cstring>
@@ -460,5 +459,3 @@ namespace std {
     }
   };
 } // namespace std
-
-#endif
diff --git a/folly/IndexedMemPool.h b/folly/IndexedMemPool.h
index f8771f33..1007eff9 100644
--- a/folly/IndexedMemPool.h
+++ b/folly/IndexedMemPool.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_INDEXEDMEMPOOL_H
-#define FOLLY_INDEXEDMEMPOOL_H
+#pragma once
 
 #include <type_traits>
 #include <stdint.h>
@@ -466,4 +465,3 @@ struct IndexedMemPoolRecycler {
 } // namespace folly
 
 # pragma GCC diagnostic pop
-#endif
diff --git a/folly/IntrusiveList.h b/folly/IntrusiveList.h
index 8d48c2aa..5a670e72 100644
--- a/folly/IntrusiveList.h
+++ b/folly/IntrusiveList.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_INTRUSIVELIST_H_
-#define FOLLY_INTRUSIVELIST_H_
+#pragma once
 
 /*
  * This file contains convenience aliases that make boost::intrusive::list
@@ -117,5 +116,3 @@ using CountedIntrusiveList = boost::intrusive::list<
     boost::intrusive::constant_time_size<true>>;
 
 } // folly
-
-#endif // FOLLY_INTRUSIVELIST_H_
diff --git a/folly/Lazy.h b/folly/Lazy.h
index 0edb2e77..1d1ba728 100644
--- a/folly/Lazy.h
+++ b/folly/Lazy.h
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#ifndef FOLLY_LAZY_H_
-#define FOLLY_LAZY_H_
+
+#pragma once
 
 #include <utility>
 #include <type_traits>
@@ -131,5 +131,3 @@ lazy(Func&& fun) {
 //////////////////////////////////////////////////////////////////////
 
 }
-
-#endif
diff --git a/folly/LifoSem.h b/folly/LifoSem.h
index 32358fcb..e5a06a92 100644
--- a/folly/LifoSem.h
+++ b/folly/LifoSem.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_LIFOSEM_H
-#define FOLLY_LIFOSEM_H
+#pragma once
 
 #include <string.h>
 #include <stdint.h>
@@ -605,5 +604,3 @@ struct LifoSemImpl : public detail::LifoSemBase<BatonType, Atom> {
 };
 
 } // namespace folly
-
-#endif
diff --git a/folly/Likely.h b/folly/Likely.h
index 0888ab7a..9a5aea99 100644
--- a/folly/Likely.h
+++ b/folly/Likely.h
@@ -21,8 +21,7 @@
  * @author Tudor Bosman (tudorb@fb.com)
  */
 
-#ifndef FOLLY_BASE_LIKELY_H_
-#define FOLLY_BASE_LIKELY_H_
+#pragma once
 
 #undef LIKELY
 #undef UNLIKELY
@@ -34,5 +33,3 @@
 #define LIKELY(x)   (x)
 #define UNLIKELY(x) (x)
 #endif
-
-#endif /* FOLLY_BASE_LIKELY_H_ */
diff --git a/folly/Logging.h b/folly/Logging.h
index f99b5030..404ca80e 100644
--- a/folly/Logging.h
+++ b/folly/Logging.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_LOGGING_H_
-#define FOLLY_LOGGING_H_
+#pragma once
 
 #include <atomic>
 #include <chrono>
@@ -54,5 +53,3 @@
           LOG(severity)
 
 #endif
-
-#endif  // FOLLY_LOGGING_H_
diff --git a/folly/Malloc.h b/folly/Malloc.h
index 87d34ab4..e7616da5 100644
--- a/folly/Malloc.h
+++ b/folly/Malloc.h
@@ -17,7 +17,7 @@
 // Functions to provide smarter use of jemalloc, if jemalloc is being used.
 // http://www.canonware.com/download/jemalloc/jemalloc-latest/doc/jemalloc.html
 
-#ifndef FOLLY_MALLOC_H_
+#pragma once
 #define FOLLY_MALLOC_H_
 
 /**
@@ -279,5 +279,3 @@ _GLIBCXX_END_NAMESPACE_VERSION
 } // folly
 
 #endif // !defined(_GLIBCXX_USE_FB) || defined(_LIBSTDCXX_FBSTRING)
-
-#endif // FOLLY_MALLOC_H_
diff --git a/folly/MapUtil.h b/folly/MapUtil.h
index d1094f51..0df5d788 100644
--- a/folly/MapUtil.h
+++ b/folly/MapUtil.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_MAPUTIL_H_
-#define FOLLY_MAPUTIL_H_
+#pragma once
 
 #include <folly/Conv.h>
 #include <folly/Optional.h>
@@ -100,5 +99,3 @@ typename Map::mapped_type* get_ptr(
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_MAPUTIL_H_ */
diff --git a/folly/Memory.h b/folly/Memory.h
index 69af41d1..193d5062 100644
--- a/folly/Memory.h
+++ b/folly/Memory.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_MEMORY_H_
-#define FOLLY_MEMORY_H_
+#pragma once
 
 #include <folly/Traits.h>
 #include <folly/portability/Memory.h>
@@ -418,5 +417,3 @@ std::shared_ptr<T> allocate_shared(Allocator&& allocator, Args&&... args) {
 template <class T> struct IsArenaAllocator : std::false_type { };
 
 }  // namespace folly
-
-#endif /* FOLLY_MEMORY_H_ */
diff --git a/folly/MemoryMapping.h b/folly/MemoryMapping.h
index 0b9bce9f..bc114d89 100644
--- a/folly/MemoryMapping.h
+++ b/folly/MemoryMapping.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_MEMORYMAPPING_H_
-#define FOLLY_MEMORYMAPPING_H_
+#pragma once
 
 #include <folly/FBString.h>
 #include <folly/File.h>
@@ -250,5 +249,3 @@ void alignedForwardMemcpy(void* dest, const void* src, size_t size);
 void mmapFileCopy(const char* src, const char* dest, mode_t mode = 0666);
 
 }  // namespace folly
-
-#endif /* FOLLY_MEMORYMAPPING_H_ */
diff --git a/folly/Merge.h b/folly/Merge.h
index 775d989b..51af2f82 100644
--- a/folly/Merge.h
+++ b/folly/Merge.h
@@ -36,8 +36,7 @@
  * from a.
  */
 
-#ifndef FOLLY_MERGE_H_
-#define FOLLY_MERGE_H_
+#pragma once
 
 #include <algorithm>
 
@@ -82,5 +81,3 @@ OutputIt merge(InputIt1 first1, InputIt1 last1,
 }
 
 }
-
-#endif
diff --git a/folly/Optional.h b/folly/Optional.h
index 2e04e332..6fc07b98 100644
--- a/folly/Optional.h
+++ b/folly/Optional.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_OPTIONAL_H_
-#define FOLLY_OPTIONAL_H_
+#pragma once
 
 /*
  * Optional - For conditional initialization of values, like boost::optional,
@@ -406,5 +405,3 @@ template<class V> bool operator> (const V& other, const Optional<V>&) = delete;
 ///////////////////////////////////////////////////////////////////////////////
 
 } // namespace folly
-
-#endif // FOLLY_OPTIONAL_H_
diff --git a/folly/PackedSyncPtr.h b/folly/PackedSyncPtr.h
index fd7424c5..74c5ab8f 100644
--- a/folly/PackedSyncPtr.h
+++ b/folly/PackedSyncPtr.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_PACKEDSYNCPTR_H_
-#define FOLLY_PACKEDSYNCPTR_H_
+#pragma once
 
 #include <folly/Portability.h>
 
@@ -147,5 +146,3 @@ static_assert(sizeof(PackedSyncPtr<void>) == 8,
               "messed up");
 
 }
-
-#endif
diff --git a/folly/Padded.h b/folly/Padded.h
index 94fc1103..d474b850 100644
--- a/folly/Padded.h
+++ b/folly/Padded.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_PADDED_H_
-#define FOLLY_PADDED_H_
+#pragma once
 
 #include <algorithm>
 #include <cassert>
@@ -512,5 +511,3 @@ class Adaptor {
 
 }  // namespace padded
 }  // namespace folly
-
-#endif /* FOLLY_PADDED_H_ */
diff --git a/folly/Portability.h b/folly/Portability.h
index 7de1d8de..c9616ea7 100644
--- a/folly/Portability.h
+++ b/folly/Portability.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_PORTABILITY_H_
-#define FOLLY_PORTABILITY_H_
+#pragma once
 
 #include <string.h>
 
@@ -365,5 +364,3 @@ using namespace FOLLY_GFLAGS_NAMESPACE;
 // we will take the next one.
 #define FOLLY_STATIC_CTOR_PRIORITY_MAX __attribute__((__init_priority__(102)))
 #endif
-
-#endif // FOLLY_PORTABILITY_H_
diff --git a/folly/Preprocessor.h b/folly/Preprocessor.h
index 49bbc710..9d098c3d 100644
--- a/folly/Preprocessor.h
+++ b/folly/Preprocessor.h
@@ -16,8 +16,7 @@
 
 // @author: Andrei Alexandrescu
 
-#ifndef FOLLY_PREPROCESSOR_
-#define FOLLY_PREPROCESSOR_
+#pragma once
 
 /**
  * Necessarily evil preprocessor-related amenities.
@@ -92,5 +91,3 @@
  * another macro expansion.
  */
 #define FB_STRINGIZE(x) #x
-
-#endif // FOLLY_PREPROCESSOR_
diff --git a/folly/ProducerConsumerQueue.h b/folly/ProducerConsumerQueue.h
index 69f3fd5a..da9b93a4 100644
--- a/folly/ProducerConsumerQueue.h
+++ b/folly/ProducerConsumerQueue.h
@@ -17,8 +17,7 @@
 // @author Bo Hu (bhu@fb.com)
 // @author Jordan DeLong (delong.j@fb.com)
 
-#ifndef PRODUCER_CONSUMER_QUEUE_H_
-#define PRODUCER_CONSUMER_QUEUE_H_
+#pragma once
 
 #include <atomic>
 #include <cassert>
@@ -174,5 +173,3 @@ private:
 };
 
 }
-
-#endif
diff --git a/folly/RWSpinLock.h b/folly/RWSpinLock.h
index a5b60534..5bbdca6f 100644
--- a/folly/RWSpinLock.h
+++ b/folly/RWSpinLock.h
@@ -81,8 +81,7 @@
  * @author Xin Liu <xliux@fb.com>
  */
 
-#ifndef FOLLY_RWSPINLOCK_H_
-#define FOLLY_RWSPINLOCK_H_
+#pragma once
 
 /*
 ========================================================================
@@ -787,5 +786,3 @@ typedef RWTicketSpinLockT<64> RWTicketSpinLock64;
 #ifdef RW_SPINLOCK_USE_X86_INTRINSIC_
 #undef RW_SPINLOCK_USE_X86_INTRINSIC_
 #endif
-
-#endif  // FOLLY_RWSPINLOCK_H_
diff --git a/folly/Random.h b/folly/Random.h
index 53283a28..0cfc5efe 100644
--- a/folly/Random.h
+++ b/folly/Random.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_RANDOM_H_
+#pragma once
 #define FOLLY_RANDOM_H_
 
 #include <type_traits>
@@ -245,5 +245,3 @@ inline uint32_t randomNumberSeed() {
 }
 
 #include <folly/Random-inl.h>
-
-#endif
diff --git a/folly/Range.h b/folly/Range.h
index 4913aef4..db2de699 100644
--- a/folly/Range.h
+++ b/folly/Range.h
@@ -17,8 +17,7 @@
 // @author Mark Rabkin (mrabkin@fb.com)
 // @author Andrei Alexandrescu (andrei.alexandrescu@fb.com)
 
-#ifndef FOLLY_RANGE_H_
-#define FOLLY_RANGE_H_
+#pragma once
 
 #include <folly/FBString.h>
 #include <folly/Portability.h>
@@ -1147,5 +1146,3 @@ struct hasher<folly::Range<T*>,
 #pragma GCC diagnostic pop
 
 FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(folly::Range);
-
-#endif // FOLLY_RANGE_H_
diff --git a/folly/SafeAssert.h b/folly/SafeAssert.h
index 65d2e9f9..39d07423 100644
--- a/folly/SafeAssert.h
+++ b/folly/SafeAssert.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SAFEASSERT_H_
-#define FOLLY_SAFEASSERT_H_
+#pragma once
 
 #include <folly/Portability.h>
 #include <folly/Preprocessor.h>
@@ -50,5 +49,3 @@ namespace folly { namespace detail {
     unsigned int line,
     const char* function);
 }}  // namespace folly
-
-#endif /* FOLLY_SAFEASSERT_H_ */
diff --git a/folly/ScopeGuard.h b/folly/ScopeGuard.h
index 8b16fae1..0e2ac6d1 100644
--- a/folly/ScopeGuard.h
+++ b/folly/ScopeGuard.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SCOPEGUARD_H_
-#define FOLLY_SCOPEGUARD_H_
+#pragma once
 
 #include <cstddef>
 #include <functional>
@@ -276,5 +275,3 @@ operator+(detail::ScopeGuardOnExit, FunctionType&& fn) {
   auto FB_ANONYMOUS_VARIABLE(SCOPE_SUCCESS_STATE) \
   = ::folly::detail::ScopeGuardOnSuccess() + [&]()
 #endif // native uncaught_exception() supported
-
-#endif // FOLLY_SCOPEGUARD_H_
diff --git a/folly/SmallLocks.h b/folly/SmallLocks.h
index 88fefe3e..fe447563 100644
--- a/folly/SmallLocks.h
+++ b/folly/SmallLocks.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SMALLLOCKS_H_
-#define FOLLY_SMALLLOCKS_H_
+#pragma once
 
 /*
  * This header defines a few very small mutex types.  These are useful
@@ -41,5 +40,3 @@
 #if FOLLY_X64 || FOLLY_A64 || FOLLY_PPC64
 #include <folly/PicoSpinLock.h>
 #endif
-
-#endif
diff --git a/folly/SparseByteSet.h b/folly/SparseByteSet.h
index bed95095..2dc55e87 100644
--- a/folly/SparseByteSet.h
+++ b/folly/SparseByteSet.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_FAST_BYTE_SET_H_
-#define FOLLY_FAST_BYTE_SET_H_
+#pragma once
 
 #include <cstdint>
 #include <glog/logging.h>
@@ -86,5 +85,3 @@ class SparseByteSet {
 };
 
 }
-
-#endif
diff --git a/folly/SpookyHashV1.h b/folly/SpookyHashV1.h
index d6c55539..2a3d8670 100644
--- a/folly/SpookyHashV1.h
+++ b/folly/SpookyHashV1.h
@@ -42,8 +42,7 @@
 // slower than MD5.
 //
 
-#ifndef FOLLY_SPOOKYHASHV1_H_
-#define FOLLY_SPOOKYHASHV1_H_
+#pragma once
 
 #include <cstddef>
 #include <cstdint>
@@ -302,5 +301,3 @@ private:
 
 }  // namespace hash
 }  // namespace folly
-
-#endif
diff --git a/folly/SpookyHashV2.h b/folly/SpookyHashV2.h
index 7344ec27..804191d1 100644
--- a/folly/SpookyHashV2.h
+++ b/folly/SpookyHashV2.h
@@ -43,8 +43,7 @@
 // slower than MD5.
 //
 
-#ifndef FOLLY_SPOOKYHASHV2_H_
-#define FOLLY_SPOOKYHASHV2_H_
+#pragma once
 
 #include <cstddef>
 #include <cstdint>
@@ -307,5 +306,3 @@ private:
 
 }  // namespace hash
 }  // namespace folly
-
-#endif
diff --git a/folly/String-inl.h b/folly/String-inl.h
index 114292d2..e3ad12b4 100644
--- a/folly/String-inl.h
+++ b/folly/String-inl.h
@@ -14,13 +14,12 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_STRING_INL_H_
-#define FOLLY_STRING_INL_H_
+#pragma once
 
 #include <stdexcept>
 #include <iterator>
 
-#ifndef FOLLY_BASE_STRING_H_
+#ifndef FOLLY_STRING_H_
 #error This file may only be included from String.h
 #endif
 
@@ -669,5 +668,3 @@ void hexDump(const void* ptr, size_t size, OutIt out) {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_STRING_INL_H_ */
diff --git a/folly/String.h b/folly/String.h
index 19a2c3b2..5a5763ca 100644
--- a/folly/String.h
+++ b/folly/String.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BASE_STRING_H_
-#define FOLLY_BASE_STRING_H_
+#pragma once
+#define FOLLY_STRING_H_
 
 #include <exception>
 #include <stdarg.h>
@@ -628,5 +628,3 @@ struct has_nothrow_constructor<folly::basic_fbstring<T> > : true_type {
 } // namespace boost
 
 #include <folly/String-inl.h>
-
-#endif
diff --git a/folly/Subprocess.h b/folly/Subprocess.h
index 22583e84..c70a1f4b 100644
--- a/folly/Subprocess.h
+++ b/folly/Subprocess.h
@@ -90,8 +90,8 @@
  * make sure to serialize your signals (i.e. kill()) with the waits --
  * either wait & signal from the same thread, or use a mutex.
  */
-#ifndef FOLLY_SUBPROCESS_H_
-#define FOLLY_SUBPROCESS_H_
+
+#pragma once
 
 #include <sys/types.h>
 #include <signal.h>
@@ -869,5 +869,3 @@ inline Subprocess::Options& Subprocess::Options::operator|=(
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_SUBPROCESS_H_ */
diff --git a/folly/Synchronized.h b/folly/Synchronized.h
index d10a97fc..5ea2ad54 100644
--- a/folly/Synchronized.h
+++ b/folly/Synchronized.h
@@ -21,8 +21,7 @@
  * @author: Andrei Alexandrescu (andrei.alexandrescu@fb.com)
  */
 
-#ifndef SYNCHRONIZED_H_
-#define SYNCHRONIZED_H_
+#pragma once
 
 #include <type_traits>
 #include <mutex>
@@ -762,5 +761,3 @@ void lockInOrder(P1& p1, P2& p2) {
             else
 
 } /* namespace folly */
-
-#endif // SYNCHRONIZED_H_
diff --git a/folly/ThreadCachedArena.h b/folly/ThreadCachedArena.h
index 50085aec..1fafe3f9 100644
--- a/folly/ThreadCachedArena.h
+++ b/folly/ThreadCachedArena.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_THREADCACHEDARENA_H_
-#define FOLLY_THREADCACHEDARENA_H_
+#pragma once
 
 #include <type_traits>
 
@@ -86,5 +85,3 @@ template <>
 struct IsArenaAllocator<ThreadCachedArena> : std::true_type { };
 
 }  // namespace folly
-
-#endif /* FOLLY_THREADCACHEDARENA_H_ */
diff --git a/folly/ThreadCachedInt.h b/folly/ThreadCachedInt.h
index 7e16d6a7..fcc4a7ea 100644
--- a/folly/ThreadCachedInt.h
+++ b/folly/ThreadCachedInt.h
@@ -20,8 +20,7 @@
  * @author Spencer Ahrens (sahrens)
  */
 
-#ifndef FOLLY_THREADCACHEDINT_H
-#define FOLLY_THREADCACHEDINT_H
+#pragma once
 
 #include <atomic>
 
@@ -175,5 +174,3 @@ class ThreadCachedInt : boost::noncopyable {
 };
 
 }
-
-#endif
diff --git a/folly/ThreadLocal.h b/folly/ThreadLocal.h
index 30b8042b..abc9b64a 100644
--- a/folly/ThreadLocal.h
+++ b/folly/ThreadLocal.h
@@ -34,8 +34,7 @@
  * @author Spencer Ahrens (sahrens)
  */
 
-#ifndef FOLLY_THREADLOCAL_H_
-#define FOLLY_THREADLOCAL_H_
+#pragma once
 
 #include <folly/Portability.h>
 #include <boost/iterator/iterator_facade.hpp>
@@ -353,5 +352,3 @@ class ThreadLocalPtr {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_THREADLOCAL_H_ */
diff --git a/folly/TimeoutQueue.h b/folly/TimeoutQueue.h
index bbf556ca..cef83a9b 100644
--- a/folly/TimeoutQueue.h
+++ b/folly/TimeoutQueue.h
@@ -25,8 +25,7 @@
  * @author Tudor Bosman (tudorb@fb.com)
  */
 
-#ifndef FOLLY_TIMEOUTQUEUE_H_
-#define FOLLY_TIMEOUTQUEUE_H_
+#pragma once
 
 #include <stdint.h>
 #include <functional>
@@ -127,5 +126,3 @@ class TimeoutQueue {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_TIMEOUTQUEUE_H_ */
diff --git a/folly/Traits.h b/folly/Traits.h
index 2d8c52dd..f34dc748 100644
--- a/folly/Traits.h
+++ b/folly/Traits.h
@@ -16,8 +16,7 @@
 
 // @author: Andrei Alexandrescu
 
-#ifndef FOLLY_BASE_TRAITS_H_
-#define FOLLY_BASE_TRAITS_H_
+#pragma once
 
 #include <memory>
 #include <limits>
@@ -481,5 +480,3 @@ FOLLY_ASSUME_FBVECTOR_COMPATIBLE_1(boost::shared_ptr);
       classname, func_name, /* nolint */ volatile); \
   FOLLY_CREATE_HAS_MEMBER_FN_TRAITS_IMPL( \
       classname, func_name, /* nolint */ volatile const)
-
-#endif //FOLLY_BASE_TRAITS_H_
diff --git a/folly/Unicode.h b/folly/Unicode.h
index d07cf310..ecd0ae10 100644
--- a/folly/Unicode.h
+++ b/folly/Unicode.h
@@ -16,8 +16,7 @@
 
 // Some utility routines relating to unicode.
 
-#ifndef FOLLY_UNICODE_H_
-#define FOLLY_UNICODE_H_
+#pragma once
 
 #include <folly/FBString.h>
 
@@ -35,5 +34,3 @@ fbstring codePointToUtf8(char32_t cp);
 //////////////////////////////////////////////////////////////////////
 
 }
-
-#endif
diff --git a/folly/Uri.h b/folly/Uri.h
index de693baa..fe88523d 100644
--- a/folly/Uri.h
+++ b/folly/Uri.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_URI_H_
+#pragma once
 #define FOLLY_URI_H_
 
 #include <folly/String.h>
@@ -119,5 +119,3 @@ class Uri {
 }  // namespace folly
 
 #include <folly/Uri-inl.h>
-
-#endif /* FOLLY_URI_H_ */
diff --git a/folly/Varint.h b/folly/Varint.h
index a9b9d0d6..d2e661eb 100644
--- a/folly/Varint.h
+++ b/folly/Varint.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_VARINT_H_
-#define FOLLY_VARINT_H_
+#pragma once
 
 #include <type_traits>
 #include <folly/Conv.h>
@@ -138,5 +137,3 @@ inline uint64_t decodeVarint(Range<T*>& data) {
 }
 
 }  // namespaces
-
-#endif /* FOLLY_VARINT_H_ */
diff --git a/folly/VersionCheck.h b/folly/VersionCheck.h
index c864e7db..9a3ce677 100644
--- a/folly/VersionCheck.h
+++ b/folly/VersionCheck.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_VERSIONCHECK_H_
-#define FOLLY_VERSIONCHECK_H_
+#pragma once
 
 #include <cstdio>
 #include <cstdlib>
@@ -107,5 +106,3 @@
     } \
   } \
   }
-
-#endif /* FOLLY_VERSIONCHECK_H_ */
diff --git a/folly/detail/AtomicHashUtils.h b/folly/detail/AtomicHashUtils.h
index bb49eef0..ba1f49a5 100644
--- a/folly/detail/AtomicHashUtils.h
+++ b/folly/detail/AtomicHashUtils.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef incl_FOLLY_ATOMIC_HASH_UTILS_H
-#define incl_FOLLY_ATOMIC_HASH_UTILS_H
+#pragma once
 
 #include <thread>
 #include <folly/portability/Asm.h>
@@ -38,5 +37,3 @@ void atomic_hash_spin_wait(Cond condition) {
 }
 
 }} // namespace folly::detail
-
-#endif
diff --git a/folly/detail/BitIteratorDetail.h b/folly/detail/BitIteratorDetail.h
index e8a0b38d..6a8b4fe6 100644
--- a/folly/detail/BitIteratorDetail.h
+++ b/folly/detail/BitIteratorDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_BITITERATORDETAIL_H_
-#define FOLLY_DETAIL_BITITERATORDETAIL_H_
+#pragma once
 
 #include <iterator>
 #include <type_traits>
@@ -88,5 +87,3 @@ struct BitIteratorBase {
 
 }  // namespace bititerator_detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_BITITERATORDETAIL_H_ */
diff --git a/folly/detail/BitsDetail.h b/folly/detail/BitsDetail.h
index a411d0a9..d89a25ef 100644
--- a/folly/detail/BitsDetail.h
+++ b/folly/detail/BitsDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_BITSDETAIL_H_
-#define FOLLY_DETAIL_BITSDETAIL_H_
+#pragma once
 
 namespace folly {
 namespace detail {
@@ -49,5 +48,3 @@ int popcountll(unsigned long long x);
 
 }  // namespace detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_BITSDETAIL_H_ */
diff --git a/folly/detail/CacheLocality.h b/folly/detail/CacheLocality.h
index db29b1bd..1ede43cb 100644
--- a/folly/detail/CacheLocality.h
+++ b/folly/detail/CacheLocality.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_CACHELOCALITY_H_
-#define FOLLY_DETAIL_CACHELOCALITY_H_
+#pragma once
 
 #include <sched.h>
 #include <algorithm>
@@ -346,5 +345,3 @@ Getcpu::Func AccessSpreader<std::atomic>::pickGetcpuFunc();
 
 } // namespace detail
 } // namespace folly
-
-#endif /* FOLLY_DETAIL_CacheLocality_H_ */
diff --git a/folly/detail/ChecksumDetail.h b/folly/detail/ChecksumDetail.h
index 9bbe22e9..540b3201 100644
--- a/folly/detail/ChecksumDetail.h
+++ b/folly/detail/ChecksumDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_CHECKSUMDETAIL_H_
-#define FOLLY_DETAIL_CHECKSUMDETAIL_H_
+#pragma once
 
 namespace folly { namespace detail {
 
@@ -54,5 +53,3 @@ uint32_t crc32c_sw(const uint8_t* data, size_t nbytes,
 
 
 }} // folly::detail
-
-#endif /* FOLLY_DETAIL_CHECKSUMDETAIL_H_ */
diff --git a/folly/detail/DiscriminatedPtrDetail.h b/folly/detail/DiscriminatedPtrDetail.h
index 2c14642d..8795321a 100644
--- a/folly/detail/DiscriminatedPtrDetail.h
+++ b/folly/detail/DiscriminatedPtrDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_DISCRIMINATEDPTRDETAIL_H_
-#define FOLLY_DETAIL_DISCRIMINATEDPTRDETAIL_H_
+#pragma once
 
 #include <utility>
 #include <type_traits>
@@ -161,5 +160,3 @@ struct ApplyConstVisitor
 
 }  // namespace dptr_detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_DISCRIMINATEDPTRDETAIL_H_ */
diff --git a/folly/detail/ExceptionWrapper.h b/folly/detail/ExceptionWrapper.h
index c38b8c75..8d5071a6 100644
--- a/folly/detail/ExceptionWrapper.h
+++ b/folly/detail/ExceptionWrapper.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_EXCEPTIONWRAPPER_H
-#define FOLLY_DETAIL_EXCEPTIONWRAPPER_H
+#pragma once
 
 namespace folly { namespace detail {
 
@@ -28,5 +27,3 @@ class Thrower {
 };
 
 }}
-
-#endif
diff --git a/folly/detail/FileUtilDetail.h b/folly/detail/FileUtilDetail.h
index 11f06ae4..b5ae6f65 100644
--- a/folly/detail/FileUtilDetail.h
+++ b/folly/detail/FileUtilDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_FILEUTILDETAIL_H_
-#define FOLLY_DETAIL_FILEUTILDETAIL_H_
+#pragma once
 
 #include <cerrno>
 #include <unistd.h>
@@ -107,5 +106,3 @@ ssize_t wrapvFull(F f, int fd, iovec* iov, int count, Offset... offset) {
 }
 
 }}  // namespaces
-
-#endif /* FOLLY_DETAIL_FILEUTILDETAIL_H_ */
diff --git a/folly/detail/FingerprintPolynomial.h b/folly/detail/FingerprintPolynomial.h
index f405fd83..588ae757 100644
--- a/folly/detail/FingerprintPolynomial.h
+++ b/folly/detail/FingerprintPolynomial.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_BUILD_FINGERPRINTPOLYNOMIAL_H_
-#define FOLLY_BUILD_FINGERPRINTPOLYNOMIAL_H_
+#pragma once
 
 #include <cstdint>
 
@@ -141,5 +140,3 @@ class FingerprintPolynomial {
 
 }  // namespace detail
 }  // namespace folly
-
-#endif /* FOLLY_BUILD_FINGERPRINTPOLYNOMIAL_H_ */
diff --git a/folly/detail/FunctionalExcept.h b/folly/detail/FunctionalExcept.h
index 575da6f3..643c8eb2 100644
--- a/folly/detail/FunctionalExcept.h
+++ b/folly/detail/FunctionalExcept.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_FUNCTIONAL_EXCEPT_H
-#define FOLLY_DETAIL_FUNCTIONAL_EXCEPT_H
+#pragma once
 
 #include <folly/Portability.h>
 
@@ -36,5 +35,3 @@ FOLLY_NAMESPACE_STD_END
 #else
 #error This file should never be included if FOLLY_HAVE_BITS_FUNCTEXCEPT_H is set
 #endif
-
-#endif
diff --git a/folly/detail/GroupVarintDetail.h b/folly/detail/GroupVarintDetail.h
index f5c68c7e..d44e7995 100644
--- a/folly/detail/GroupVarintDetail.h
+++ b/folly/detail/GroupVarintDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_GROUPVARINTDETAIL_H_
-#define FOLLY_DETAIL_GROUPVARINTDETAIL_H_
+#pragma once
 
 #include <stddef.h>
 
@@ -99,5 +98,3 @@ class GroupVarintBase {
 
 }  // namespace detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_GROUPVARINTDETAIL_H_ */
diff --git a/folly/detail/Malloc.h b/folly/detail/Malloc.h
index 1136c832..4a7fa73b 100644
--- a/folly/detail/Malloc.h
+++ b/folly/detail/Malloc.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_MALLOC_H
-#define FOLLY_DETAIL_MALLOC_H
+#pragma once
 
 #include <stdlib.h>
 
@@ -84,5 +83,3 @@ extern int (*mallctlbymib)(const size_t*, size_t, void*, size_t*, void*,
 #endif
 
 }
-
-#endif
diff --git a/folly/detail/MemoryIdler.h b/folly/detail/MemoryIdler.h
index 4b11c720..e4bebc34 100644
--- a/folly/detail/MemoryIdler.h
+++ b/folly/detail/MemoryIdler.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_MEMORYIDLER_H
-#define FOLLY_DETAIL_MEMORYIDLER_H
+#pragma once
 
 #include <atomic>
 #include <chrono>
@@ -149,5 +148,3 @@ struct MemoryIdler {
 };
 
 }} // namespace folly::detail
-
-#endif
diff --git a/folly/detail/RangeCommon.h b/folly/detail/RangeCommon.h
index 9e670046..f7c8a4a5 100644
--- a/folly/detail/RangeCommon.h
+++ b/folly/detail/RangeCommon.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_RANGE_COMMON_H_
-#define FOLLY_DETAIL_RANGE_COMMON_H_
+#pragma once
 
 #include <algorithm>
 #include <string>
@@ -86,5 +85,3 @@ inline size_t qfind_first_byte_of_nosse(const StringPieceLite haystack,
 }
 
 }
-
-#endif
diff --git a/folly/detail/RangeSse42.h b/folly/detail/RangeSse42.h
index 142f057d..e0578202 100644
--- a/folly/detail/RangeSse42.h
+++ b/folly/detail/RangeSse42.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_RANGE_SSE42_H_
-#define FOLLY_DETAIL_RANGE_SSE42_H_
+#pragma once
 
 #include <cstddef>
 #include <folly/detail/RangeCommon.h>
@@ -30,5 +29,3 @@ size_t qfind_first_byte_of_sse42(const StringPieceLite haystack,
 }
 
 }
-
-#endif
diff --git a/folly/detail/SlowFingerprint.h b/folly/detail/SlowFingerprint.h
index 73e19252..1bbbda61 100644
--- a/folly/detail/SlowFingerprint.h
+++ b/folly/detail/SlowFingerprint.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_SLOWFINGERPRINT_H_
-#define FOLLY_DETAIL_SLOWFINGERPRINT_H_
+#pragma once
 
 #include <folly/Fingerprint.h>
 #include <folly/detail/FingerprintPolynomial.h>
@@ -88,5 +87,3 @@ class SlowFingerprint {
 
 }  // namespace detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_SLOWFINGERPRINT_H_ */
diff --git a/folly/detail/Stats.h b/folly/detail/Stats.h
index 5d960664..1620cb5d 100644
--- a/folly/detail/Stats.h
+++ b/folly/detail/Stats.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_STATS_H_
-#define FOLLY_DETAIL_STATS_H_
+#pragma once
 
 #include <chrono>
 #include <cstdint>
@@ -123,5 +122,3 @@ struct Bucket {
 };
 
 }} // folly::detail
-
-#endif // FOLLY_DETAIL_STATS_H_
diff --git a/folly/detail/ThreadLocalDetail.h b/folly/detail/ThreadLocalDetail.h
index 57d1767e..23c566f0 100644
--- a/folly/detail/ThreadLocalDetail.h
+++ b/folly/detail/ThreadLocalDetail.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_THREADLOCALDETAIL_H_
-#define FOLLY_DETAIL_THREADLOCALDETAIL_H_
+#pragma once
 
 #include <limits.h>
 #include <pthread.h>
@@ -359,5 +358,3 @@ struct StaticMeta : StaticMetaBase {
 
 }  // namespace threadlocal_detail
 }  // namespace folly
-
-#endif /* FOLLY_DETAIL_THREADLOCALDETAIL_H_ */
diff --git a/folly/detail/UncaughtExceptionCounter.h b/folly/detail/UncaughtExceptionCounter.h
index b0119c06..0fb76c7a 100644
--- a/folly/detail/UncaughtExceptionCounter.h
+++ b/folly/detail/UncaughtExceptionCounter.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DETAIL_UNCAUGHTEXCEPTIONCOUNTER_H_
-#define FOLLY_DETAIL_UNCAUGHTEXCEPTIONCOUNTER_H_
+#pragma once
 
 #include <exception>
 
@@ -93,5 +92,3 @@ inline int UncaughtExceptionCounter::getUncaughtExceptionCount() noexcept {
 }
 
 }} // namespaces
-
-#endif /* FOLLY_DETAIL_UNCAUGHTEXCEPTIONCOUNTER_H_ */
diff --git a/folly/dynamic-inl.h b/folly/dynamic-inl.h
index cea7f283..b357d3ee 100644
--- a/folly/dynamic-inl.h
+++ b/folly/dynamic-inl.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_DYNAMIC_INL_H_
-#define FOLLY_DYNAMIC_INL_H_
+#pragma once
 
 #include <functional>
 #include <boost/iterator/iterator_adaptor.hpp>
@@ -874,5 +873,3 @@ class FormatValue<detail::DefaultValueWrapper<dynamic, V>> {
 }  // namespaces
 
 #undef FB_DYNAMIC_APPLY
-
-#endif
diff --git a/folly/dynamic.h b/folly/dynamic.h
index ef4fdf68..c2ab2a4b 100644
--- a/folly/dynamic.h
+++ b/folly/dynamic.h
@@ -60,8 +60,7 @@
  * @author Jordan DeLong <delong.j@fb.com>
  */
 
-#ifndef FOLLY_DYNAMIC_H_
-#define FOLLY_DYNAMIC_H_
+#pragma once
 
 #include <cstdint>
 #include <initializer_list>
@@ -588,5 +587,3 @@ private:
 }
 
 #include <folly/dynamic-inl.h>
-
-#endif
diff --git a/folly/experimental/BitVectorCoding.h b/folly/experimental/BitVectorCoding.h
index 7dcd3340..738e820a 100644
--- a/folly/experimental/BitVectorCoding.h
+++ b/folly/experimental/BitVectorCoding.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_BIT_VECTOR_CODING_H
-#define FOLLY_EXPERIMENTAL_BIT_VECTOR_CODING_H
+#pragma once
 
 #include <cstdlib>
 #include <limits>
@@ -448,5 +447,3 @@ class BitVectorReader {
 };
 
 }}  // namespaces
-
-#endif  // FOLLY_EXPERIMENTAL_BIT_VECTOR_CODING_H
diff --git a/folly/experimental/Bits.h b/folly/experimental/Bits.h
index 19c1de28..50836ed8 100644
--- a/folly/experimental/Bits.h
+++ b/folly/experimental/Bits.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_BITS_H_
-#define FOLLY_EXPERIMENTAL_BITS_H_
+#pragma once
 
 #include <cstddef>
 #include <type_traits>
@@ -304,5 +303,3 @@ inline size_t Bits<T, Traits>::count(const T* begin, const T* end) {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_EXPERIMENTAL_BITS_H_ */
diff --git a/folly/experimental/EliasFanoCoding.h b/folly/experimental/EliasFanoCoding.h
index c586a6d5..9f3b8744 100644
--- a/folly/experimental/EliasFanoCoding.h
+++ b/folly/experimental/EliasFanoCoding.h
@@ -21,8 +21,7 @@
  * "Quasi-succinct indices" (arxiv:1206.4300).
  */
 
-#ifndef FOLLY_EXPERIMENTAL_ELIAS_FANO_CODING_H
-#define FOLLY_EXPERIMENTAL_ELIAS_FANO_CODING_H
+#pragma once
 
 #include <cstdlib>
 #include <limits>
@@ -684,5 +683,3 @@ class EliasFanoReader {
 };
 
 }}  // namespaces
-
-#endif  // FOLLY_EXPERIMENTAL_ELIAS_FANO_CODING_H
diff --git a/folly/experimental/EventCount.h b/folly/experimental/EventCount.h
index 8c9fde82..e0f5a94d 100644
--- a/folly/experimental/EventCount.h
+++ b/folly/experimental/EventCount.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_EVENTCOUNT_H_
-#define FOLLY_EXPERIMENTAL_EVENTCOUNT_H_
+#pragma once
 
 #include <unistd.h>
 #include <syscall.h>
@@ -210,5 +209,3 @@ void EventCount::await(Condition condition) {
 }
 
 }  // namespace folly
-
-#endif /* FOLLY_EXPERIMENTAL_EVENTCOUNT_H_ */
diff --git a/folly/experimental/FunctionScheduler.h b/folly/experimental/FunctionScheduler.h
index 08976f07..e3c0d132 100644
--- a/folly/experimental/FunctionScheduler.h
+++ b/folly/experimental/FunctionScheduler.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_FUNCTION_SCHEDULER_H_
-#define FOLLY_EXPERIMENTAL_FUNCTION_SCHEDULER_H_
+#pragma once
 
 #include <folly/Range.h>
 #include <chrono>
@@ -263,5 +262,3 @@ class FunctionScheduler {
 };
 
 }
-
-#endif
diff --git a/folly/experimental/Instructions.h b/folly/experimental/Instructions.h
index 732dd253..97386ff1 100644
--- a/folly/experimental/Instructions.h
+++ b/folly/experimental/Instructions.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
-#define FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
+#pragma once
 
 #include <glog/logging.h>
 
@@ -75,5 +74,3 @@ struct Haswell : public Nehalem {
 };
 
 }}}  // namespaces
-
-#endif  // FOLLY_EXPERIMENTAL_INSTRUCTIONS_H
diff --git a/folly/experimental/NestedCommandLineApp.h b/folly/experimental/NestedCommandLineApp.h
index daa1188c..0a807a21 100644
--- a/folly/experimental/NestedCommandLineApp.h
+++ b/folly/experimental/NestedCommandLineApp.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_NESTEDCOMMANDLINEAPP_H_
-#define FOLLY_NESTEDCOMMANDLINEAPP_H_
+#pragma once
 
 #include <functional>
 #include <stdexcept>
@@ -151,5 +150,3 @@ class NestedCommandLineApp {
 };
 
 }  // namespaces
-
-#endif /* FOLLY_NESTEDCOMMANDLINEAPP_H_ */
diff --git a/folly/experimental/ProgramOptions.h b/folly/experimental/ProgramOptions.h
index 355b66f0..b51b9899 100644
--- a/folly/experimental/ProgramOptions.h
+++ b/folly/experimental/ProgramOptions.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_PROGRAMOPTIONS_H_
-#define FOLLY_PROGRAMOPTIONS_H_
+#pragma once
 
 #include <boost/program_options.hpp>
 #include <folly/Optional.h>
@@ -83,5 +82,3 @@ NestedCommandLineParseResult parseNestedCommandLine(
     const boost::program_options::options_description& desc);
 
 }  // namespaces
-
-#endif /* FOLLY_PROGRAMOPTIONS_H_ */
diff --git a/folly/experimental/Select64.h b/folly/experimental/Select64.h
index bee6970b..9c2e03f9 100644
--- a/folly/experimental/Select64.h
+++ b/folly/experimental/Select64.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_SELECT64_H
-#define FOLLY_EXPERIMENTAL_SELECT64_H
+#pragma once
 
 #include <glog/logging.h>
 
@@ -77,5 +76,3 @@ inline uint64_t select64<compression::instructions::Haswell>(uint64_t x,
 }
 
 } // namespace folly
-
-#endif
diff --git a/folly/experimental/StringKeyedCommon.h b/folly/experimental/StringKeyedCommon.h
index f6816c9d..26eed9ef 100644
--- a/folly/experimental/StringKeyedCommon.h
+++ b/folly/experimental/StringKeyedCommon.h
@@ -16,8 +16,7 @@
 // Copyright 2013-present Facebook. All Rights Reserved.
 // @author: Pavlo Kushnir (pavlo)
 
-#ifndef FOLLY_EXPERIMENTAL_STRINGKEYEDCOMMON_H_
-#define FOLLY_EXPERIMENTAL_STRINGKEYEDCOMMON_H_
+#pragma once
 
 #include <memory>
 #include <folly/Range.h>
@@ -40,5 +39,3 @@ void stringPieceDel(StringPiece piece, const Alloc& alloc) {
 }
 
 } // folly
-
-#endif /* FOLLY_EXPERIMENTAL_STRINGKEYEDCOMMON_H_ */
diff --git a/folly/experimental/StringKeyedMap.h b/folly/experimental/StringKeyedMap.h
index 1481c1e7..93d4559c 100644
--- a/folly/experimental/StringKeyedMap.h
+++ b/folly/experimental/StringKeyedMap.h
@@ -16,8 +16,7 @@
 // Copyright 2013-present Facebook. All Rights Reserved.
 // @author: Pavlo Kushnir (pavlo)
 
-#ifndef FOLLY_EXPERIMENTAL_STRINGKEYEDMAP_H_
-#define FOLLY_EXPERIMENTAL_STRINGKEYEDMAP_H_
+#pragma once
 
 #include <initializer_list>
 #include <memory>
@@ -200,5 +199,3 @@ public:
 };
 
 } // folly
-
-#endif /* FOLLY_EXPERIMENTAL_STRINGKEYEDMAP_H_ */
diff --git a/folly/experimental/StringKeyedSet.h b/folly/experimental/StringKeyedSet.h
index 0b7abbbc..f7e433bc 100644
--- a/folly/experimental/StringKeyedSet.h
+++ b/folly/experimental/StringKeyedSet.h
@@ -16,8 +16,7 @@
 // Copyright 2013-present Facebook. All Rights Reserved.
 // @author: Pavlo Kushnir (pavlo)
 
-#ifndef FOLLY_EXPERIMENTAL_STRINGKEYEDSET_H_
-#define FOLLY_EXPERIMENTAL_STRINGKEYEDSET_H_
+#pragma once
 
 #include <initializer_list>
 #include <memory>
@@ -185,5 +184,3 @@ public:
 using StringKeyedSet = StringKeyedSetBase<>;
 
 } // folly
-
-#endif /* FOLLY_EXPERIMENTAL_STRINGKEYEDSET_H_ */
diff --git a/folly/experimental/StringKeyedUnorderedMap.h b/folly/experimental/StringKeyedUnorderedMap.h
index e31f96f5..59aa139f 100644
--- a/folly/experimental/StringKeyedUnorderedMap.h
+++ b/folly/experimental/StringKeyedUnorderedMap.h
@@ -16,8 +16,7 @@
 // Copyright 2013-present Facebook. All Rights Reserved.
 // @author: Pavlo Kushnir (pavlo)
 
-#ifndef FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDMAP_H_
-#define FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDMAP_H_
+#pragma once
 
 #include <initializer_list>
 #include <memory>
@@ -227,5 +226,3 @@ public:
 };
 
 } // folly
-
-#endif /* FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDMAP_H_ */
diff --git a/folly/experimental/StringKeyedUnorderedSet.h b/folly/experimental/StringKeyedUnorderedSet.h
index 1b33bfbf..e52feaa5 100644
--- a/folly/experimental/StringKeyedUnorderedSet.h
+++ b/folly/experimental/StringKeyedUnorderedSet.h
@@ -16,8 +16,7 @@
 // Copyright 2013-present Facebook. All Rights Reserved.
 // @author: Pavlo Kushnir (pavlo)
 
-#ifndef FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDSET_H_
-#define FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDSET_H_
+#pragma once
 
 #include <initializer_list>
 #include <memory>
@@ -221,5 +220,3 @@ public:
 typedef BasicStringKeyedUnorderedSet<> StringKeyedUnorderedSet;
 
 } // folly
-
-#endif /* FOLLY_EXPERIMENTAL_STRINGKEYEDUNORDEREDSET_H_ */
diff --git a/folly/experimental/TestUtil.h b/folly/experimental/TestUtil.h
index 98af4c41..f5fb1638 100644
--- a/folly/experimental/TestUtil.h
+++ b/folly/experimental/TestUtil.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TESTUTIL_H_
-#define FOLLY_TESTUTIL_H_
+#pragma once
 
 #include <map>
 #include <string>
@@ -213,5 +212,3 @@ private:
 
 }  // namespace test
 }  // namespace folly
-
-#endif /* FOLLY_TESTUTIL_H_ */
diff --git a/folly/experimental/TupleOps.h b/folly/experimental/TupleOps.h
index c9b05bf8..65e30863 100644
--- a/folly/experimental/TupleOps.h
+++ b/folly/experimental/TupleOps.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TUPLEOPS_H_
-#define FOLLY_TUPLEOPS_H_
+#pragma once
 
 #include <limits>
 #include <tuple>
@@ -123,5 +122,3 @@ auto tuplePrepend(T&& car, U&& cdr)
 }
 
 }  // namespaces
-
-#endif /* FOLLY_TUPLEOPS_H_ */
diff --git a/folly/experimental/exception_tracer/ExceptionAbi.h b/folly/experimental/exception_tracer/ExceptionAbi.h
index 0fbea89f..9cee64fc 100644
--- a/folly/experimental/exception_tracer/ExceptionAbi.h
+++ b/folly/experimental/exception_tracer/ExceptionAbi.h
@@ -14,9 +14,7 @@
  * limitations under the License.
  */
 
-
-#ifndef FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONABI_H_
-#define FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONABI_H_
+#pragma once
 
 // A clone of the relevant parts of unwind-cxx.h from libstdc++
 // The layout of these structures is defined by the ABI.
@@ -56,5 +54,3 @@ __cxa_eh_globals* __cxa_get_globals_fast(void) noexcept;
 }
 
 }  // namespace __cxxabiv1
-
-#endif /* FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONABI_H_ */
diff --git a/folly/experimental/exception_tracer/ExceptionTracer.h b/folly/experimental/exception_tracer/ExceptionTracer.h
index 3b7416a3..f356b9bb 100644
--- a/folly/experimental/exception_tracer/ExceptionTracer.h
+++ b/folly/experimental/exception_tracer/ExceptionTracer.h
@@ -17,8 +17,7 @@
 //
 // Exception tracer library.
 
-#ifndef FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACER_H_
-#define FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACER_H_
+#pragma once
 
 #include <cstdint>
 #include <iosfwd>
@@ -51,5 +50,3 @@ void installHandlers();
 
 }  // namespace exception_tracer
 }  // namespace folly
-
-#endif /* FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACER_H_ */
diff --git a/folly/experimental/exception_tracer/ExceptionTracerLib.h b/folly/experimental/exception_tracer/ExceptionTracerLib.h
index 72d16311..73d1f3a3 100644
--- a/folly/experimental/exception_tracer/ExceptionTracerLib.h
+++ b/folly/experimental/exception_tracer/ExceptionTracerLib.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACERLIB_H_
-#define FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACERLIB_H_
+#pragma once
 
 #include <typeinfo>
 #include <exception>
@@ -50,5 +49,3 @@ void registerCxaEndCatchCallback(CxaEndCatchType callback);
 void registerRethrowExceptionCallback(RethrowExceptionType callback);
 }
 }
-
-#endif /* FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_EXCEPTIONTRACERLIB_H_ */
diff --git a/folly/experimental/exception_tracer/StackTrace.h b/folly/experimental/exception_tracer/StackTrace.h
index 4a7e58f7..11a60648 100644
--- a/folly/experimental/exception_tracer/StackTrace.h
+++ b/folly/experimental/exception_tracer/StackTrace.h
@@ -14,9 +14,7 @@
  * limitations under the License.
  */
 
-
-#ifndef FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_STACKTRACE_H_
-#define FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_STACKTRACE_H_
+#pragma once
 
 #include <cassert>
 #include <cstddef>
@@ -98,5 +96,3 @@ class StackTraceStack {
 };
 
 }}  // namespaces
-
-#endif /* FOLLY_EXPERIMENTAL_EXCEPTION_TRACER_STACKTRACE_H_ */
diff --git a/folly/experimental/io/AsyncIO.h b/folly/experimental/io/AsyncIO.h
index 6b3dfe0b..6a9ee6a4 100644
--- a/folly/experimental/io/AsyncIO.h
+++ b/folly/experimental/io/AsyncIO.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_ASYNCIO_H_
-#define FOLLY_IO_ASYNCIO_H_
+#pragma once
 
 #include <sys/types.h>
 #include <sys/uio.h>
@@ -251,5 +250,3 @@ class AsyncIOQueue {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_IO_ASYNCIO_H_ */
diff --git a/folly/experimental/io/FsUtil.h b/folly/experimental/io/FsUtil.h
index fe677921..85606d1c 100644
--- a/folly/experimental/io/FsUtil.h
+++ b/folly/experimental/io/FsUtil.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_FSUTIL_H_
-#define FOLLY_IO_FSUTIL_H_
+#pragma once
 
 #include <boost/filesystem.hpp>
 
@@ -68,5 +67,3 @@ path executable_path();
 
 }  // namespace fs
 }  // namespace folly
-
-#endif /* FOLLY_IO_FSUTIL_H_ */
diff --git a/folly/experimental/io/HugePages.h b/folly/experimental/io/HugePages.h
index d1d23178..8d5619a2 100644
--- a/folly/experimental/io/HugePages.h
+++ b/folly/experimental/io/HugePages.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_HUGEPAGES_H_
-#define FOLLY_IO_HUGEPAGES_H_
+#pragma once
 
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -79,5 +78,3 @@ const HugePageSize* getHugePageSize(size_t size = 0);
 const HugePageSize* getHugePageSizeForDevice(dev_t device);
 
 }  // namespace folly
-
-#endif /* FOLLY_IO_HUGEPAGES_H_ */
diff --git a/folly/experimental/symbolizer/Dwarf.h b/folly/experimental/symbolizer/Dwarf.h
index ba48486f..ed7d1ae8 100644
--- a/folly/experimental/symbolizer/Dwarf.h
+++ b/folly/experimental/symbolizer/Dwarf.h
@@ -16,8 +16,7 @@
 
 // DWARF record parser
 
-#ifndef FOLLY_EXPERIMENTAL_SYMBOLIZER_DWARF_H_
-#define FOLLY_EXPERIMENTAL_SYMBOLIZER_DWARF_H_
+#pragma once
 
 #include <boost/variant.hpp>
 
@@ -276,5 +275,3 @@ inline std::ostream& operator<<(std::ostream& out, const Dwarf::Path& path) {
 
 }  // namespace symbolizer
 }  // namespace folly
-
-#endif /* FOLLY_EXPERIMENTAL_SYMBOLIZER_DWARF_H_ */
diff --git a/folly/experimental/symbolizer/Elf.h b/folly/experimental/symbolizer/Elf.h
index 9e2908dc..176a9e89 100644
--- a/folly/experimental/symbolizer/Elf.h
+++ b/folly/experimental/symbolizer/Elf.h
@@ -16,7 +16,7 @@
 
 // ELF file parser
 
-#ifndef FOLLY_EXPERIMENTAL_SYMBOLIZER_ELF_H_
+#pragma once
 #define FOLLY_EXPERIMENTAL_SYMBOLIZER_ELF_H_
 
 #include <stdio.h>
@@ -241,5 +241,3 @@ class ElfFile {
 }  // namespace folly
 
 #include <folly/experimental/symbolizer/Elf-inl.h>
-
-#endif /* FOLLY_EXPERIMENTAL_SYMBOLIZER_ELF_H_ */
diff --git a/folly/experimental/symbolizer/ElfCache.h b/folly/experimental/symbolizer/ElfCache.h
index 671b263b..eb01d210 100644
--- a/folly/experimental/symbolizer/ElfCache.h
+++ b/folly/experimental/symbolizer/ElfCache.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYMBOLIZER_ELFCACHE_H_
-#define FOLLY_SYMBOLIZER_ELFCACHE_H_
+#pragma once
 
 #include <cstring>
 #include <limits.h>  // for PATH_MAX
@@ -130,5 +129,3 @@ class ElfCache : public ElfCacheBase {
 };
 
 }}  // namespaces
-
-#endif /* FOLLY_SYMBOLIZER_ELFCACHE_H_ */
diff --git a/folly/experimental/symbolizer/LineReader.h b/folly/experimental/symbolizer/LineReader.h
index c1efb4e3..6137627e 100644
--- a/folly/experimental/symbolizer/LineReader.h
+++ b/folly/experimental/symbolizer/LineReader.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYMBOLIZER_LINEREADER_H_
-#define FOLLY_SYMBOLIZER_LINEREADER_H_
+#pragma once
 
 #include <cstddef>
 
@@ -86,5 +85,3 @@ class LineReader : private boost::noncopyable {
 };
 
 }}  // namespaces
-
-#endif /* FOLLY_SYMBOLIZER_LINEREADER_H_ */
diff --git a/folly/experimental/symbolizer/SignalHandler.h b/folly/experimental/symbolizer/SignalHandler.h
index 1dad2173..726c8a81 100644
--- a/folly/experimental/symbolizer/SignalHandler.h
+++ b/folly/experimental/symbolizer/SignalHandler.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYMBOLIZER_SIGNALHANDLER_H_
-#define FOLLY_SYMBOLIZER_SIGNALHANDLER_H_
+#pragma once
 
 #include <functional>
 
@@ -51,5 +50,3 @@ void installFatalSignalCallbacks();
 
 
 }}  // namespaces
-
-#endif /* FOLLY_SYMBOLIZER_SIGNALHANDLER_H_ */
diff --git a/folly/experimental/symbolizer/StackTrace.h b/folly/experimental/symbolizer/StackTrace.h
index 8f6c28a3..9fc8afa7 100644
--- a/folly/experimental/symbolizer/StackTrace.h
+++ b/folly/experimental/symbolizer/StackTrace.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYMBOLIZER_STACKTRACE_H_
-#define FOLLY_SYMBOLIZER_STACKTRACE_H_
+#pragma once
 
 #include <cstdint>
 #include <cstdlib>
@@ -45,5 +44,3 @@ ssize_t getStackTrace(uintptr_t* addresses, size_t maxAddresses);
 ssize_t getStackTraceSafe(uintptr_t* addresses, size_t maxAddresses);
 
 }}  // namespaces
-
-#endif /* FOLLY_SYMBOLIZER_STACKTRACE_H_ */
diff --git a/folly/experimental/symbolizer/Symbolizer.h b/folly/experimental/symbolizer/Symbolizer.h
index cad7013e..232cb30b 100644
--- a/folly/experimental/symbolizer/Symbolizer.h
+++ b/folly/experimental/symbolizer/Symbolizer.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_SYMBOLIZER_SYMBOLIZER_H_
-#define FOLLY_EXPERIMENTAL_SYMBOLIZER_SYMBOLIZER_H_
+#pragma once
 
 #include <array>
 #include <cstdint>
@@ -295,5 +294,3 @@ class StringSymbolizePrinter : public SymbolizePrinter {
 
 }  // namespace symbolizer
 }  // namespace folly
-
-#endif /* FOLLY_EXPERIMENTAL_SYMBOLIZER_SYMBOLIZER_H_ */
diff --git a/folly/experimental/symbolizer/test/SignalHandlerTest.h b/folly/experimental/symbolizer/test/SignalHandlerTest.h
index 2a195a98..6a7d8b7a 100644
--- a/folly/experimental/symbolizer/test/SignalHandlerTest.h
+++ b/folly/experimental/symbolizer/test/SignalHandlerTest.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYMBOLIZER_TEST_SIGNALHANDLERTEST_H_
-#define FOLLY_SYMBOLIZER_TEST_SIGNALHANDLERTEST_H_
+#pragma once
 
 namespace folly { namespace symbolizer { namespace test {
 
@@ -24,5 +23,3 @@ inline void failHard() {
 }
 
 }}}  // namespaces
-
-#endif /* FOLLY_SYMBOLIZER_TEST_SIGNALHANDLERTEST_H_ */
diff --git a/folly/experimental/test/CodingTestUtils.h b/folly/experimental/test/CodingTestUtils.h
index 9c25ad1a..d16f31e7 100644
--- a/folly/experimental/test/CodingTestUtils.h
+++ b/folly/experimental/test/CodingTestUtils.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_EXPERIMENTAL_CODING_TEST_UTILS_H
-#define FOLLY_EXPERIMENTAL_CODING_TEST_UTILS_H
+#pragma once
 
 #include <algorithm>
 #include <fstream>
@@ -371,5 +370,3 @@ void bmJumpTo(const List& list, const std::vector<uint32_t>& data,
 }
 
 }}  // namespaces
-
-#endif  // FOLLY_EXPERIMENTAL_CODING_TEST_UTILS_H
diff --git a/folly/gen/Base-inl.h b/folly/gen/Base-inl.h
index 3b756fbc..11308b3e 100644
--- a/folly/gen/Base-inl.h
+++ b/folly/gen/Base-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_BASE_H
+#ifndef FOLLY_GEN_BASE_H_
 #error This file may only be included from folly/gen/Base.h
 #endif
 
diff --git a/folly/gen/Base.h b/folly/gen/Base.h
index 9cd8e8f0..6cf05d17 100644
--- a/folly/gen/Base.h
+++ b/folly/gen/Base.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_BASE_H
-#define FOLLY_GEN_BASE_H
+#pragma once
+#define FOLLY_GEN_BASE_H_
 
 #include <algorithm>
 #include <functional>
@@ -826,5 +826,3 @@ UnwrapOr unwrapOr(Fallback&& fallback) {
 }} // folly::gen
 
 #include <folly/gen/Base-inl.h>
-
-#endif // FOLLY_GEN_BASE_H
diff --git a/folly/gen/Combine-inl.h b/folly/gen/Combine-inl.h
index 0ce96b0e..994d93c9 100644
--- a/folly/gen/Combine-inl.h
+++ b/folly/gen/Combine-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_COMBINE_H
+#ifndef FOLLY_GEN_COMBINE_H_
 #error This file may only be included from folly/gen/Combine.h
 #endif
 
diff --git a/folly/gen/Combine.h b/folly/gen/Combine.h
index 243350d8..bd9362e2 100644
--- a/folly/gen/Combine.h
+++ b/folly/gen/Combine.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_COMBINE_H
-#define FOLLY_GEN_COMBINE_H
+#pragma once
+#define FOLLY_GEN_COMBINE_H_
 
 #include <folly/gen/Base.h>
 
@@ -42,5 +42,3 @@ Interleave interleave(Source2&& source2) {
 }  // namespace folly
 
 #include <folly/gen/Combine-inl.h>
-
-#endif // FOLLY_GEN_COMBINE_H
diff --git a/folly/gen/Core-inl.h b/folly/gen/Core-inl.h
index 8e6f02f2..4f22d9b3 100644
--- a/folly/gen/Core-inl.h
+++ b/folly/gen/Core-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_CORE_H
+#ifndef FOLLY_GEN_CORE_H_
 #error This file may only be included from folly/gen/Core.h
 #endif
 
diff --git a/folly/gen/Core.h b/folly/gen/Core.h
index 59455da2..6bfc7cf0 100644
--- a/folly/gen/Core.h
+++ b/folly/gen/Core.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_CORE_H
-#define FOLLY_GEN_CORE_H
+#pragma once
+#define FOLLY_GEN_CORE_H_
 
 namespace folly { namespace gen {
 
@@ -41,5 +41,3 @@ class Chain;
 }} // folly::gen
 
 #include <folly/gen/Core-inl.h>
-
-#endif // FOLLY_GEN_CORE_H
diff --git a/folly/gen/File-inl.h b/folly/gen/File-inl.h
index 4de5f588..98981ef9 100644
--- a/folly/gen/File-inl.h
+++ b/folly/gen/File-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_FILE_H
+#ifndef FOLLY_GEN_FILE_H_
 #error This file may only be included from folly/gen/File.h
 #endif
 
diff --git a/folly/gen/File.h b/folly/gen/File.h
index 1c5a36d4..cc031698 100644
--- a/folly/gen/File.h
+++ b/folly/gen/File.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_FILE_H
-#define FOLLY_GEN_FILE_H
+#pragma once
+#define FOLLY_GEN_FILE_H_
 
 #include <folly/File.h>
 #include <folly/gen/Base.h>
@@ -68,5 +68,3 @@ S toFile(File file, std::unique_ptr<IOBuf> buffer) {
 }}  // !folly::gen
 
 #include <folly/gen/File-inl.h>
-
-#endif // FOLLY_GEN_FILE_H
diff --git a/folly/gen/Parallel.h b/folly/gen/Parallel.h
index 74cf955e..106ae945 100644
--- a/folly/gen/Parallel.h
+++ b/folly/gen/Parallel.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_PARALLEL_H_
+#pragma once
 #define FOLLY_GEN_PARALLEL_H_
 
 #include <mutex>
@@ -106,5 +106,3 @@ Sub sub(Sink sink) {
 }} // !namespace folly::gen
 
 #include <folly/gen/Parallel-inl.h>
-
-#endif /* FOLLY_GEN_PARALLEL_H_ */
diff --git a/folly/gen/ParallelMap-inl.h b/folly/gen/ParallelMap-inl.h
index fcabf5b9..eb2899cd 100644
--- a/folly/gen/ParallelMap-inl.h
+++ b/folly/gen/ParallelMap-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_PARALLELMAP_H
+#ifndef FOLLY_GEN_PARALLELMAP_H_
 #error This file may only be included from folly/gen/ParallelMap.h
 #endif
 
diff --git a/folly/gen/ParallelMap.h b/folly/gen/ParallelMap.h
index 35aa970b..9a3e3c7e 100644
--- a/folly/gen/ParallelMap.h
+++ b/folly/gen/ParallelMap.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_PARALLELMAP_H
-#define FOLLY_GEN_PARALLELMAP_H
+#pragma once
+#define FOLLY_GEN_PARALLELMAP_H_
 
 #include <folly/gen/Core.h>
 
@@ -46,5 +46,3 @@ template<class Predicate,
 }}  // namespaces
 
 #include <folly/gen/ParallelMap-inl.h>
-
-#endif  // FOLLY_GEN_PARALLELMAP_H
diff --git a/folly/gen/String-inl.h b/folly/gen/String-inl.h
index 64cd3cc0..e87974da 100644
--- a/folly/gen/String-inl.h
+++ b/folly/gen/String-inl.h
@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_STRING_H
+#ifndef FOLLY_GEN_STRING_H_
 #error This file may only be included from folly/gen/String.h
 #endif
 
diff --git a/folly/gen/String.h b/folly/gen/String.h
index 40ce1712..ac3c2998 100644
--- a/folly/gen/String.h
+++ b/folly/gen/String.h
@@ -14,8 +14,8 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_STRING_H
-#define FOLLY_GEN_STRING_H
+#pragma once
+#define FOLLY_GEN_STRING_H_
 
 #include <folly/Range.h>
 #include <folly/gen/Base.h>
@@ -246,5 +246,3 @@ StreamSplitter<Callback> streamSplitter(char delimiter,
 }  // namespace folly
 
 #include <folly/gen/String-inl.h>
-
-#endif // FOLLY_GEN_STRING_H
diff --git a/folly/gen/test/Bench.h b/folly/gen/test/Bench.h
index d86a7efa..a4104598 100644
--- a/folly/gen/test/Bench.h
+++ b/folly/gen/test/Bench.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GEN_BENCH_H_
-#define FOLLY_GEN_BENCH_H_
+#pragma once
 
 #include <folly/Benchmark.h>
 
@@ -31,5 +30,3 @@ static bool FB_ANONYMOUS_VARIABLE(benchGen) = (             \
     }), true)
 #define BENCH_GEN(gen) BENCH_GEN_IMPL(gen, "")
 #define BENCH_GEN_REL(gen) BENCH_GEN_IMPL(gen, "%")
-
-#endif
diff --git a/folly/init/Init.h b/folly/init/Init.h
index 8c1bc7e5..52e96f25 100644
--- a/folly/init/Init.h
+++ b/folly/init/Init.h
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#ifndef INIT_LIGHT_BASE_H
-#define INIT_LIGHT_BASE_H
+
+#pragma once
 
 /*
  * Calls common init functions in the necessary order
@@ -31,5 +31,3 @@ namespace folly {
 void init(int* argc, char*** argv, bool removeFlags = true);
 
 } // folly
-
-#endif
diff --git a/folly/io/Compression.h b/folly/io/Compression.h
index 540a08a1..3575d8e4 100644
--- a/folly/io/Compression.h
+++ b/folly/io/Compression.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_COMPRESSION_H_
-#define FOLLY_IO_COMPRESSION_H_
+#pragma once
 
 #include <cstdint>
 #include <limits>
@@ -180,5 +179,3 @@ std::unique_ptr<Codec> getCodec(CodecType type,
                                 int level = COMPRESSION_LEVEL_DEFAULT);
 
 }}  // namespaces
-
-#endif /* FOLLY_IO_COMPRESSION_H_ */
diff --git a/folly/io/Cursor.h b/folly/io/Cursor.h
index d1ec9636..74412ea6 100644
--- a/folly/io/Cursor.h
+++ b/folly/io/Cursor.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_CURSOR_H
-#define FOLLY_CURSOR_H
+#pragma once
 
 #include <assert.h>
 #include <cstdarg>
@@ -922,5 +921,3 @@ class QueueAppender : public detail::Writable<QueueAppender> {
 };
 
 }}  // folly::io
-
-#endif // FOLLY_CURSOR_H
diff --git a/folly/io/IOBuf.h b/folly/io/IOBuf.h
index 5262fb5f..f6a43d66 100644
--- a/folly/io/IOBuf.h
+++ b/folly/io/IOBuf.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_IOBUF_H_
-#define FOLLY_IO_IOBUF_H_
+#pragma once
 
 #include <glog/logging.h>
 #include <atomic>
@@ -1467,5 +1466,3 @@ inline IOBuf::Iterator IOBuf::end() const { return cend(); }
 } // folly
 
 #pragma GCC diagnostic pop
-
-#endif // FOLLY_IO_IOBUF_H_
diff --git a/folly/io/IOBufQueue.h b/folly/io/IOBufQueue.h
index 81ffe92a..d421f917 100644
--- a/folly/io/IOBufQueue.h
+++ b/folly/io/IOBufQueue.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_IOBUF_QUEUE_H
-#define FOLLY_IO_IOBUF_QUEUE_H
+#pragma once
 
 #include <folly/io/IOBuf.h>
 
@@ -295,5 +294,3 @@ class IOBufQueue {
 };
 
 } // folly
-
-#endif // FOLLY_IO_IOBUF_QUEUE_H
diff --git a/folly/io/RecordIO.h b/folly/io/RecordIO.h
index faf89029..6a89ce81 100644
--- a/folly/io/RecordIO.h
+++ b/folly/io/RecordIO.h
@@ -22,7 +22,8 @@
  * or deleted chunks of the file, or modified data.  When reading, you may lose
  * corrupted records, but the stream will resynchronize automatically.
  */
-#ifndef FOLLY_IO_RECORDIO_H_
+
+#pragma once
 #define FOLLY_IO_RECORDIO_H_
 
 #include <atomic>
@@ -176,5 +177,3 @@ RecordInfo validateRecord(ByteRange range, uint32_t fileId);
 }  // namespaces
 
 #include <folly/io/RecordIO-inl.h>
-
-#endif /* FOLLY_IO_RECORDIO_H_ */
diff --git a/folly/io/TypedIOBuf.h b/folly/io/TypedIOBuf.h
index e958490c..0a58bbc6 100644
--- a/folly/io/TypedIOBuf.h
+++ b/folly/io/TypedIOBuf.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_IO_TYPEDIOBUF_H_
-#define FOLLY_IO_TYPEDIOBUF_H_
+#pragma once
 
 #include <algorithm>
 #include <iterator>
@@ -214,5 +213,3 @@ class TypedIOBuf {
 };
 
 }  // namespace folly
-
-#endif /* FOLLY_IO_TYPEDIOBUF_H_ */
diff --git a/folly/json.h b/folly/json.h
index 2854b76a..b3ed871a 100644
--- a/folly/json.h
+++ b/folly/json.h
@@ -38,8 +38,7 @@
  * @author Jordan DeLong <delong.j@fb.com>
  */
 
-#ifndef FOLLY_JSON_H_
-#define FOLLY_JSON_H_
+#pragma once
 
 #include <iosfwd>
 
@@ -168,5 +167,3 @@ void PrintTo(const dynamic&, std::ostream*);
 //////////////////////////////////////////////////////////////////////
 
 }
-
-#endif
diff --git a/folly/portability/Constexpr.h b/folly/portability/Constexpr.h
index 7ea46300..3625e265 100755
--- a/folly/portability/Constexpr.h
+++ b/folly/portability/Constexpr.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_CONSTEXPR_H_
-#define FOLLY_CONSTEXPR_H_
+#pragma once
 
 #include <cstdint>
 #include <cstring>
@@ -50,5 +49,3 @@ constexpr size_t constexpr_strlen(const char* s) {
 #endif
 }
 }
-
-#endif
diff --git a/folly/portability/GFlags.h b/folly/portability/GFlags.h
index 976ecccc..d28c6a28 100644
--- a/folly/portability/GFlags.h
+++ b/folly/portability/GFlags.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_GFLAGS_H_
-#define FOLLY_GFLAGS_H_
+#pragma once
 
 #include <folly/Portability.h>
 
@@ -24,5 +23,3 @@
 #else
 #define DEFINE_int32(_name, _default, _description) int FLAGS_##_name = _default
 #endif
-
-#endif
diff --git a/folly/portability/SysUio.h b/folly/portability/SysUio.h
index e0ab7f37..9640f680 100644
--- a/folly/portability/SysUio.h
+++ b/folly/portability/SysUio.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_SYSUIO_H_
-#define FOLLY_SYSUIO_H_
+#pragma once
 
 #include <sys/uio.h>
 
@@ -27,5 +26,3 @@ constexpr size_t kIovMax = IOV_MAX;
 constexpr size_t kIovMax = UIO_MAXIOV;
 #endif
 }
-
-#endif
diff --git a/folly/small_vector.h b/folly/small_vector.h
index 4707a146..b81d318a 100644
--- a/folly/small_vector.h
+++ b/folly/small_vector.h
@@ -20,8 +20,8 @@
  *
  * @author Jordan DeLong <delong.j@fb.com>
  */
-#ifndef FOLLY_SMALL_VECTOR_H_
-#define FOLLY_SMALL_VECTOR_H_
+
+#pragma once
 
 #include <stdexcept>
 #include <cstdlib>
@@ -1160,5 +1160,3 @@ struct IndexableTraits<small_vector<T, M, A, B, C>>
 # undef FB_PACK_PUSH
 # undef FB_PACK_POP
 #endif
-
-#endif
diff --git a/folly/sorted_vector_types.h b/folly/sorted_vector_types.h
index 99019d0d..b9354b10 100644
--- a/folly/sorted_vector_types.h
+++ b/folly/sorted_vector_types.h
@@ -57,8 +57,7 @@
  *     std::vector<>, which requires it to be Assignable.)
  */
 
-#ifndef FOLLY_SORTED_VECTOR_TYPES_H_
-#define FOLLY_SORTED_VECTOR_TYPES_H_
+#pragma once
 
 #include <algorithm>
 #include <initializer_list>
@@ -654,5 +653,3 @@ inline void swap(sorted_vector_map<K,V,C,A,G>& a,
 //////////////////////////////////////////////////////////////////////
 
 }
-
-#endif
diff --git a/folly/stats/BucketedTimeSeries-defs.h b/folly/stats/BucketedTimeSeries-defs.h
index e9a749a7..a726f2ee 100644
--- a/folly/stats/BucketedTimeSeries-defs.h
+++ b/folly/stats/BucketedTimeSeries-defs.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_STATS_BUCKETEDTIMESERIES_INL_H_
-#define FOLLY_STATS_BUCKETEDTIMESERIES_INL_H_
+#pragma once
 
 #include <algorithm>
 #include <glog/logging.h>
@@ -461,5 +460,3 @@ void BucketedTimeSeries<VT, TT>::forEachBucket(TimeType start, TimeType end,
 }
 
 } // folly
-
-#endif // FOLLY_STATS_BUCKETEDTIMESERIES_INL_H_
diff --git a/folly/stats/BucketedTimeSeries.h b/folly/stats/BucketedTimeSeries.h
index 8ce00b2b..c3c2c1e4 100644
--- a/folly/stats/BucketedTimeSeries.h
+++ b/folly/stats/BucketedTimeSeries.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_STATS_BUCKETEDTIMESERIES_H_
-#define FOLLY_STATS_BUCKETEDTIMESERIES_H_
+#pragma once
 
 #include <chrono>
 #include <vector>
@@ -406,5 +405,3 @@ class BucketedTimeSeries {
 };
 
 } // folly
-
-#endif // FOLLY_STATS_BUCKETEDTIMESERIES_H_
diff --git a/folly/stats/Histogram-defs.h b/folly/stats/Histogram-defs.h
index fe102bf2..8d4af44f 100644
--- a/folly/stats/Histogram-defs.h
+++ b/folly/stats/Histogram-defs.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_HISTOGRAM_DEFS_H_
-#define FOLLY_HISTOGRAM_DEFS_H_
+#pragma once
 
 #include <folly/Conv.h>
 
@@ -278,5 +277,3 @@ void Histogram<T>::toTSV(std::ostream& out, bool skipEmptyBuckets) const {
 }
 
 } // folly
-
-#endif // FOLLY_HISTOGRAM_DEFS_H_
diff --git a/folly/stats/Histogram.h b/folly/stats/Histogram.h
index beda7c82..0b9baba1 100644
--- a/folly/stats/Histogram.h
+++ b/folly/stats/Histogram.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_HISTOGRAM_H_
-#define FOLLY_HISTOGRAM_H_
+#pragma once
 
 #include <cstddef>
 #include <limits>
@@ -466,5 +465,3 @@ class Histogram {
 };
 
 } // folly
-
-#endif // FOLLY_HISTOGRAM_H_
diff --git a/folly/stats/MultiLevelTimeSeries-defs.h b/folly/stats/MultiLevelTimeSeries-defs.h
index 396c9049..686dafa6 100644
--- a/folly/stats/MultiLevelTimeSeries-defs.h
+++ b/folly/stats/MultiLevelTimeSeries-defs.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_STATS_MULTILEVELTIMESERIES_DEFS_H_
-#define FOLLY_STATS_MULTILEVELTIMESERIES_DEFS_H_
+#pragma once
 
 #include <glog/logging.h>
 
@@ -100,5 +99,3 @@ void MultiLevelTimeSeries<VT, TT>::clear() {
 }
 
 }  // folly
-
-#endif // FOLLY_STATS_MULTILEVELTIMESERIES_DEFS_H_
diff --git a/folly/stats/MultiLevelTimeSeries.h b/folly/stats/MultiLevelTimeSeries.h
index e8de4443..f38b4e9f 100644
--- a/folly/stats/MultiLevelTimeSeries.h
+++ b/folly/stats/MultiLevelTimeSeries.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_STATS_MULTILEVELTIMESERIES_H_
-#define FOLLY_STATS_MULTILEVELTIMESERIES_H_
+#pragma once
 
 #include <chrono>
 #include <string>
@@ -311,5 +310,3 @@ class MultiLevelTimeSeries {
 };
 
 } // folly
-
-#endif // FOLLY_STATS_MULTILEVELTIMESERIES_H_
diff --git a/folly/stats/TimeseriesHistogram-defs.h b/folly/stats/TimeseriesHistogram-defs.h
index ff88c0e6..f546d8bc 100644
--- a/folly/stats/TimeseriesHistogram-defs.h
+++ b/folly/stats/TimeseriesHistogram-defs.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TIMESERIES_HISTOGRAM_DEF_H_
-#define FOLLY_TIMESERIES_HISTOGRAM_DEF_H_
+#pragma once
 
 #include <folly/Conv.h>
 #include <folly/stats/Histogram-defs.h>
@@ -227,5 +226,3 @@ std::string TimeseriesHistogram<T, TT, C>::getString(TimeType start,
 }
 
 }  // namespace folly
-
-#endif
diff --git a/folly/stats/TimeseriesHistogram.h b/folly/stats/TimeseriesHistogram.h
index 7f58b0d2..2f3cc75f 100644
--- a/folly/stats/TimeseriesHistogram.h
+++ b/folly/stats/TimeseriesHistogram.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TIMESERIES_HISTOGRAM_H_
-#define FOLLY_TIMESERIES_HISTOGRAM_H_
+#pragma once
 
 #include <string>
 #include <boost/static_assert.hpp>
@@ -331,5 +330,3 @@ class TimeseriesHistogram {
 };
 
 }  // folly
-
-#endif  // FOLLY_TIMESERIES_HISTOGRAM_H_
diff --git a/folly/test/SynchronizedTestLib-inl.h b/folly/test/SynchronizedTestLib-inl.h
index 5399f127..1517730e 100644
--- a/folly/test/SynchronizedTestLib-inl.h
+++ b/folly/test/SynchronizedTestLib-inl.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TEST_SYNCHRONIZEDTESTLIB_INL_H
-#define FOLLY_TEST_SYNCHRONIZEDTESTLIB_INL_H
+#pragma once
 
 #include <gtest/gtest.h>
 
@@ -353,6 +352,3 @@ template <class Mutex> void testInPlaceConstruction() {
     folly::construct_in_place, 5, "a"
   );
 }
-
-
-#endif  /* FOLLY_TEST_SYNCHRONIZEDTESTLIB_INL_H */
diff --git a/folly/test/SynchronizedTestLib.h b/folly/test/SynchronizedTestLib.h
index 349ed12b..8e73273d 100644
--- a/folly/test/SynchronizedTestLib.h
+++ b/folly/test/SynchronizedTestLib.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TEST_SYNCHRONIZEDTESTLIB_H
-#define FOLLY_TEST_SYNCHRONIZEDTESTLIB_H
+#pragma once
 
 // We have mutex types outside of folly that we want to test with Synchronized.
 // Make it easy for mutex implementators to test their classes with
@@ -47,5 +46,3 @@ template <class Mutex> void testConstCopy();
 template <class Mutex> void testInPlaceConstruction();
 
 #include <folly/test/SynchronizedTestLib-inl.h>
-
-#endif /* FOLLY_TEST_SYNCHRONIZEDTESTLIB_H */
diff --git a/folly/test/TestUtils.h b/folly/test/TestUtils.h
index 1c7b4acd..14a6012d 100644
--- a/folly/test/TestUtils.h
+++ b/folly/test/TestUtils.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef FOLLY_TESTUTILS_H
-#define FOLLY_TESTUTILS_H
+#pragma once
 
 #include <gtest/gtest.h>
 
@@ -25,5 +24,3 @@
 // a normal test failure; there is only an effect if the test framework
 // interprets the message.
 #define SKIP() GTEST_FATAL_FAILURE_("Test skipped by client")
-
-#endif // FOLLY_TESTUTILS_H
diff --git a/folly/test/function_benchmark/benchmark_impl.h b/folly/test/function_benchmark/benchmark_impl.h
index d7766fbc..b6865f7a 100644
--- a/folly/test/function_benchmark/benchmark_impl.h
+++ b/folly/test/function_benchmark/benchmark_impl.h
@@ -13,8 +13,8 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-#ifndef BENCHMARK_IMPL_H_
-#define BENCHMARK_IMPL_H_
+
+#pragma once
 
 #include <functional>
 
@@ -49,5 +49,3 @@ void BM_invoke_fn_template_impl(int iters, const T& fn) {
     fn();
   }
 }
-
-#endif // BENCHMARK_IMPL_H_
diff --git a/folly/test/function_benchmark/test_functions.h b/folly/test/function_benchmark/test_functions.h
index 382ac39d..e248aa63 100644
--- a/folly/test/function_benchmark/test_functions.h
+++ b/folly/test/function_benchmark/test_functions.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef TEST_FUNCTIONS_H_
-#define TEST_FUNCTIONS_H_
+#pragma once
 
 #include <exception>
 #include <functional>
@@ -54,5 +53,3 @@ class LargeClass {
   // Avoid small object optimization.
   char data[1024];
 };
-
-#endif // TEST_FUNCTIONS_H_