diff --git a/bolt/test/AArch64/test-indirect-branch.s b/bolt/test/AArch64/test-indirect-branch.s
@@ -0,0 +1,83 @@
+// Test how BOLT handles indirect branch sequence of instructions in
+// AArch64MCPlus builder.
+
+// clang-format off
+
+// REQUIRES: system-linux
+// RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown %s -o %t.o
+// RUN: %clang %cflags --target=aarch64-unknown-linux %t.o -o %t.exe -Wl,-q
+// RUN: llvm-bolt %t.exe -o %t.bolt --print-cfg --strict\
+// RUN:  -v=1 2>&1 | FileCheck %s
+
+// Pattern 1: there is no shift amount after the 'add' instruction.
+//
+//   adr     x6, 0x219fb0 <sigall_set+0x88>
+//   add     x6, x6, x14, lsl #2
+//   ldr     w7, [x6]
+//   add     x6, x6, w7, sxtw => no shift amount
+//   br      x6
+//
+
+// Pattern 2: nop/adr pair is used in place of adrp/add
+//
+//  nop   => nop/adr instead of adrp/add
+//  adr     x13, 0x215a18 <_nl_value_type_LC_COLLATE+0x50>
+//  ldrh    w13, [x13, w12, uxtw #1]
+//  adr     x12, 0x247b30 <__gettextparse+0x5b0>
+//  add     x13, x12, w13, sxth #2
+//  br      x13
+
+  .section .text
+  .align 4
+  .globl _start
+  .type  _start, %function
+_start:
+  bl      test1
+  bl      test2
+// mov x0, #4
+// mov w8, #93
+// svc #0
+
+// Pattern 1
+// CHECK: BOLT-WARNING: Failed to match indirect branch: ShiftVAL != 2
+  .globl test1
+  .type  test1, %function
+test1:
+  mov     x1, #0
+  adr     x3, datatable
+  add     x3, x3, x1, lsl #2
+  ldr     w2, [x3]
+  add     x3, x3, w2, sxtw
+  br      x3
+test1_0:
+   ret
+test1_1:
+   ret
+test1_2:
+   ret
+
+// Pattern 2
+// CHECK: BOLT-WARNING: Failed to match indirect branch: nop/adr instead of adrp/add
+  .globl test2
+  .type  test2, %function
+test2:
+  nop
+  adr     x3, jump_table
+  ldrh    w3, [x3, x1, lsl #1]
+  adr     x1, test2_0
+  add     x3, x1, w3, sxth #2
+  br      x3
+test2_0:
+  ret
+test2_1:
+  ret
+
+  .section .rodata,"a",@progbits
+datatable:
+  .word test1_0-datatable
+  .word test1_1-datatable
+  .word test1_2-datatable
+
+jump_table:
+  .hword  (test2_0-test2_0)>>2
+  .hword  (test2_1-test2_0)>>2
diff --git a/bolt/test/X86/register-fragments-bolt-symbols.s b/bolt/test/X86/register-fragments-bolt-symbols.s
@@ -13,8 +13,12 @@
 # PREAGGWARM: B X:0 #chain.warm# 1 0
 # RUN: perf2bolt %t.warm.bolt -p %t.preagg.warm --pa -o %t.warm.fdata -w %t.warm.yaml \
 # RUN:   -v=1 | FileCheck %s --check-prefix=CHECK-BOLT-WARM
+# RUN: FileCheck %s --input-file %t.warm.fdata --check-prefix=CHECK-FDATA-WARM
+# RUN: FileCheck %s --input-file %t.warm.yaml --check-prefix=CHECK-YAML-WARM
 
 # CHECK-BOLT-WARM: marking chain.warm/1(*2) as a fragment of chain
+# CHECK-FDATA-WARM: chain
+# CHECK-YAML-WARM: chain
 
 # RUN: sed -i 's|chain|chain/2|g' %t.fdata
 # RUN: llvm-objcopy --localize-symbol=chain %t.main.o

diff --git a/clang-tools-extra/clangd/support/ThreadsafeFS.cpp b/clang-tools-extra/clangd/support/ThreadsafeFS.cpp
@@ -41,7 +41,7 @@ class VolatileFileSystem : public llvm::vfs::ProxyFileSystem {
     llvm::StringRef FileName = llvm::sys::path::filename(Path);
     if (FileName.starts_with("preamble-") && FileName.ends_with(".pch"))
       return File;
-    return std::unique_ptr<VolatileFile>(new VolatileFile(std::move(*File)));
+    return std::make_unique<VolatileFile>(std::move(*File));
   }
 
 private:

diff --git a/clang/cmake/caches/Fuchsia-stage2.cmake b/clang/cmake/caches/Fuchsia-stage2.cmake
@@ -141,7 +141,7 @@ if(WIN32 OR LLVM_WINSYSROOT)
   set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS ${WINDOWS_LINK_FLAGS} CACHE STRING "")
 endif()
 
-foreach(target aarch64-unknown-linux-gnu;armv7-unknown-linux-gnueabihf;i386-unknown-linux-gnu;riscv64-unknown-linux-gnu;x86_64-unknown-linux-gnu)
+foreach(target aarch64-linux-gnu;armv7-linux-gnueabihf;i386-linux-gnu;riscv64-linux-gnu;x86_64-linux-gnu)
   if(LINUX_${target}_SYSROOT)
     # Set the per-target builtins options.
     list(APPEND BUILTIN_TARGETS "${target}")

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -236,9 +236,6 @@ C++20 Feature Support
   ``<expected>`` from libstdc++ to work correctly with Clang.
 
 - User defined constructors are allowed for copy-list-initialization with CTAD.
-  The example code for deduction guides for std::map in
-  (`cppreference <https://en.cppreference.com/w/cpp/container/map/deduction_guides>`_)
-  will now work.
   (#GH62925).
 
 C++23 Feature Support
@@ -272,6 +269,7 @@ C++2c Feature Support
 
 - Implemented `P2809R3: Trivial infinite loops are not Undefined Behavior <https://wg21.link/P2809R3>`_.
 
+- Implemented `P3144R2 Deleting a Pointer to an Incomplete Type Should be Ill-formed <https://wg21.link/P3144R2>`_.
 
 Resolutions to C++ Defect Reports
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -438,6 +436,12 @@ New Compiler Flags
   Matches MSVC behaviour by defining ``__STDC__`` to ``1`` when
   MSVC compatibility mode is used. It has no effect for C++ code.
 
+- ``-Wc++23-compat`` group was added to help migrating existing codebases
+  to C++23.
+
+- ``-Wc++2c-compat`` group was added to help migrating existing codebases
+  to upcoming C++26.
+
 Deprecated Compiler Flags
 -------------------------
 
@@ -476,6 +480,10 @@ Modified Compiler Flags
   evaluating to ``true`` and an empty body such as ``while(1);``)
   are considered infinite, even when the ``-ffinite-loop`` flag is set.
 
+- Diagnostics groups about compatibility with a particular C++ Standard version
+  now include dianostics about C++26 features that are not present in older
+  versions.
+
 Removed Compiler Flags
 -------------------------
 
@@ -963,6 +971,10 @@ Bug Fixes to C++ Support
 - Fixed an assertion failure about invalid conversion when calling lambda. (#GH96205).
 - Fixed a bug where the first operand of binary ``operator&`` would be transformed as if it was the operand
   of the address of operator. (#GH97483).
+- Fixed an assertion failure about a constant expression which is a known integer but is not
+  evaluated to an integer. (#GH96670).
+- Fixed a bug where references to lambda capture inside a ``noexcept`` specifier were not correctly
+  instantiated. (#GH95735).
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

diff --git a/clang/include/clang/AST/ASTConsumer.h b/clang/include/clang/AST/ASTConsumer.h
@@ -23,6 +23,7 @@ namespace clang {
   class ASTDeserializationListener; // layering violation because void* is ugly
   class SemaConsumer; // layering violation required for safe SemaConsumer
   class TagDecl;
+  class DeclaratorDecl;
   class VarDecl;
   class FunctionDecl;
   class ImportDecl;
@@ -105,7 +106,7 @@ class ASTConsumer {
   /// CompleteExternalDeclaration - Callback invoked at the end of a translation
   /// unit to notify the consumer that the given external declaration should be
   /// completed.
-  virtual void CompleteExternalDeclaration(VarDecl *D) {}
+  virtual void CompleteExternalDeclaration(DeclaratorDecl *D) {}
 
   /// Callback invoked when an MSInheritanceAttr has been attached to a
   /// CXXRecordDecl.

diff --git a/clang/include/clang/Basic/DiagnosticCommonKinds.td b/clang/include/clang/Basic/DiagnosticCommonKinds.td
@@ -367,6 +367,15 @@ def warn_target_unrecognized_env : Warning<
 def err_target_unsupported_abi_with_fpu : Error<
   "'%0' ABI is not supported with FPU">;
 
+def err_ppc_impossible_musttail: Error<
+  "'musttail' attribute for this call is impossible because %select{"
+  "long calls can not be tail called on PPC|"
+  "indirect calls can not be tail called on PPC|"
+  "external calls can not be tail called on PPC}0"
+  >;
+def err_aix_musttail_unsupported: Error<
+  "'musttail' attribute is not supported on AIX">;
+
 // Source manager
 def err_cannot_open_file : Error<"cannot open file '%0': %1">, DefaultFatal;
 def err_file_modified : Error<

diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -344,7 +344,8 @@ def CXX98Compat : DiagGroup<"c++98-compat",
                              CXXPre14Compat,
                              CXXPre17Compat,
                              CXXPre20Compat,
-                             CXXPre23Compat]>;
+                             CXXPre23Compat,
+                             CXXPre26Compat]>;
 // Warnings for C++11 features which are Extensions in C++98 mode.
 def CXX98CompatPedantic : DiagGroup<"c++98-compat-pedantic",
                                     [CXX98Compat,
@@ -353,7 +354,8 @@ def CXX98CompatPedantic : DiagGroup<"c++98-compat-pedantic",
                                      CXXPre14CompatPedantic,
                                      CXXPre17CompatPedantic,
                                      CXXPre20CompatPedantic,
-                                     CXXPre23CompatPedantic]>;
+                                     CXXPre23CompatPedantic,
+                                     CXXPre26CompatPedantic]>;
 
 def CXX11NarrowingConstReference : DiagGroup<"c++11-narrowing-const-reference">;
 def CXX11Narrowing : DiagGroup<"c++11-narrowing", [CXX11NarrowingConstReference]>;
@@ -384,42 +386,54 @@ def CXX11Compat : DiagGroup<"c++11-compat",
                              CXXPre14Compat,
                              CXXPre17Compat,
                              CXXPre20Compat,
-                             CXXPre23Compat]>;
+                             CXXPre23Compat,
+                             CXXPre26Compat]>;
 def : DiagGroup<"c++0x-compat", [CXX11Compat]>;
 def CXX11CompatPedantic : DiagGroup<"c++11-compat-pedantic",
                                     [CXX11Compat,
                                      CXXPre14CompatPedantic,
                                      CXXPre17CompatPedantic,
                                      CXXPre20CompatPedantic,
-                                     CXXPre23CompatPedantic]>;
+                                     CXXPre23CompatPedantic,
+                                     CXXPre26CompatPedantic]>;
 
 def CXX14Compat : DiagGroup<"c++14-compat", [CXXPre17Compat,
                                              CXXPre20Compat,
-                                             CXXPre23Compat]>;
+                                             CXXPre23Compat,
+                                             CXXPre26Compat]>;
 def CXX14CompatPedantic : DiagGroup<"c++14-compat-pedantic",
                                     [CXX14Compat,
                                      CXXPre17CompatPedantic,
                                      CXXPre20CompatPedantic,
-                                     CXXPre23CompatPedantic]>;
+                                     CXXPre23CompatPedantic,
+                                     CXXPre26CompatPedantic]>;
 
 def CXX17Compat : DiagGroup<"c++17-compat", [DeprecatedRegister,
                                              DeprecatedIncrementBool,
                                              CXX17CompatMangling,
                                              CXXPre20Compat,
-                                             CXXPre23Compat]>;
+                                             CXXPre23Compat,
+                                             CXXPre26Compat]>;
 def CXX17CompatPedantic : DiagGroup<"c++17-compat-pedantic",
                                     [CXX17Compat,
                                      CXXPre20CompatPedantic,
-                                     CXXPre23CompatPedantic]>;
+                                     CXXPre23CompatPedantic,
+                                     CXXPre26CompatPedantic]>;
 def : DiagGroup<"c++1z-compat", [CXX17Compat]>;
 
-def CXX20Compat : DiagGroup<"c++20-compat", [CXXPre23Compat]>;
+def CXX20Compat : DiagGroup<"c++20-compat", [CXXPre23Compat,
+                                             CXXPre26Compat]>;
 def CXX20CompatPedantic : DiagGroup<"c++20-compat-pedantic",
                                     [CXX20Compat,
-                                     CXXPre23CompatPedantic]>;
+                                     CXXPre23CompatPedantic,
+                                     CXXPre26CompatPedantic]>;
 def : DiagGroup<"c++2a-compat", [CXX20Compat]>;
 def : DiagGroup<"c++2a-compat-pedantic", [CXX20CompatPedantic]>;
 
+def CXX23Compat : DiagGroup<"c++23-compat", [CXXPre26Compat]>;
+
+def CXX26Compat : DiagGroup<"c++2c-compat", [DeleteIncomplete]>;
+
 def ExitTimeDestructors : DiagGroup<"exit-time-destructors">;
 def FlexibleArrayExtensions : DiagGroup<"flexible-array-extensions">;
 def FourByteMultiChar : DiagGroup<"four-char-constants">;

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -7989,8 +7989,11 @@ def ext_delete_void_ptr_operand : ExtWarn<
 def err_ambiguous_delete_operand : Error<
   "ambiguous conversion of delete expression of type %0 to a pointer">;
 def warn_delete_incomplete : Warning<
-  "deleting pointer to incomplete type %0 may cause undefined behavior">,
+  "deleting pointer to incomplete type %0 is incompatible with C++2c"
+  " and may cause undefined behavior">,
   InGroup<DeleteIncomplete>;
+def err_delete_incomplete : Error<
+  "cannot delete pointer to incomplete type %0">;
 def err_delete_incomplete_class_type : Error<
   "deleting incomplete class type %0; no conversions to pointer type">;
 def err_delete_explicit_conversion : Error<

diff --git a/clang/include/clang/Frontend/MultiplexConsumer.h b/clang/include/clang/Frontend/MultiplexConsumer.h
@@ -67,7 +67,7 @@ class MultiplexConsumer : public SemaConsumer {
   void HandleTopLevelDeclInObjCContainer(DeclGroupRef D) override;
   void HandleImplicitImportDecl(ImportDecl *D) override;
   void CompleteTentativeDefinition(VarDecl *D) override;
-  void CompleteExternalDeclaration(VarDecl *D) override;
+  void CompleteExternalDeclaration(DeclaratorDecl *D) override;
   void AssignInheritanceModel(CXXRecordDecl *RD) override;
   void HandleVTable(CXXRecordDecl *RD) override;
   ASTMutationListener *GetASTMutationListener() override;

diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
@@ -3098,7 +3098,7 @@ class Sema final : public SemaBase {
   TentativeDefinitionsType TentativeDefinitions;
 
   /// All the external declarations encoutered and used in the TU.
-  SmallVector<VarDecl *, 4> ExternalDeclarations;
+  SmallVector<DeclaratorDecl *, 4> ExternalDeclarations;
 
   /// Generally null except when we temporarily switch decl contexts,
   /// like in \see SemaObjC::ActOnObjCTemporaryExitContainerContext.

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
@@ -15859,9 +15859,12 @@ static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
 
   if (const auto *CE = dyn_cast<ConstantExpr>(Exp)) {
     if (CE->hasAPValueResult()) {
-      Result.Val = CE->getAPValueResult();
-      IsConst = true;
-      return true;
+      APValue APV = CE->getAPValueResult();
+      if (!APV.isLValue()) {
+        Result.Val = std::move(APV);
+        IsConst = true;
+        return true;
+      }
     }
 
     // The SubExpr is usually just an IntegerLiteral.

diff --git a/clang/lib/AST/Interp/Compiler.cpp b/clang/lib/AST/Interp/Compiler.cpp
@@ -3995,7 +3995,7 @@ bool Compiler<Emitter>::VisitCXXThisExpr(const CXXThisExpr *E) {
     }
 
     for (unsigned I = StartIndex, N = InitStack.size(); I != N; ++I) {
-      if (!InitStack[I].emit<Emitter>(this, E))
+      if (!InitStack[I].template emit<Emitter>(this, E))
         return false;
     }
     return true;

diff --git a/clang/lib/AST/JSONNodeDumper.cpp b/clang/lib/AST/JSONNodeDumper.cpp
@@ -237,7 +237,7 @@ void JSONNodeDumper::Visit(const APValue &Value, QualType Ty) {
   std::string Str;
   llvm::raw_string_ostream OS(Str);
   Value.printPretty(OS, Ctx, Ty);
-  JOS.attribute("value", OS.str());
+  JOS.attribute("value", Str);
 }
 
 void JSONNodeDumper::Visit(const ConceptReference *CR) {
@@ -802,7 +802,7 @@ void JSONNodeDumper::VisitTemplateSpecializationType(
   std::string Str;
   llvm::raw_string_ostream OS(Str);
   TST->getTemplateName().print(OS, PrintPolicy);
-  JOS.attribute("templateName", OS.str());
+  JOS.attribute("templateName", Str);
 }
 
 void JSONNodeDumper::VisitInjectedClassNameType(
@@ -824,7 +824,7 @@ void JSONNodeDumper::VisitElaboratedType(const ElaboratedType *ET) {
     std::string Str;
     llvm::raw_string_ostream OS(Str);
     NNS->print(OS, PrintPolicy, /*ResolveTemplateArgs*/ true);
-    JOS.attribute("qualifier", OS.str());
+    JOS.attribute("qualifier", Str);
   }
   if (const TagDecl *TD = ET->getOwnedTagDecl())
     JOS.attribute("ownedTagDecl", createBareDeclRef(TD));
@@ -1246,7 +1246,7 @@ void JSONNodeDumper::VisitObjCMessageExpr(const ObjCMessageExpr *OME) {
   llvm::raw_string_ostream OS(Str);
 
   OME->getSelector().print(OS);
-  JOS.attribute("selector", OS.str());
+  JOS.attribute("selector", Str);
 
   switch (OME->getReceiverKind()) {
   case ObjCMessageExpr::Instance:
@@ -1277,7 +1277,7 @@ void JSONNodeDumper::VisitObjCBoxedExpr(const ObjCBoxedExpr *OBE) {
     llvm::raw_string_ostream OS(Str);
 
     MD->getSelector().print(OS);
-    JOS.attribute("selector", OS.str());
+    JOS.attribute("selector", Str);
   }
 }
 
@@ -1286,7 +1286,7 @@ void JSONNodeDumper::VisitObjCSelectorExpr(const ObjCSelectorExpr *OSE) {
   llvm::raw_string_ostream OS(Str);
 
   OSE->getSelector().print(OS);
-  JOS.attribute("selector", OS.str());
+  JOS.attribute("selector", Str);
 }
 
 void JSONNodeDumper::VisitObjCProtocolExpr(const ObjCProtocolExpr *OPE) {
@@ -1634,7 +1634,7 @@ void JSONNodeDumper::VisitStringLiteral(const StringLiteral *SL) {
   std::string Buffer;
   llvm::raw_string_ostream SS(Buffer);
   SL->outputString(SS);
-  JOS.attribute("value", SS.str());
+  JOS.attribute("value", Buffer);
 }
 void JSONNodeDumper::VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *BLE) {
   JOS.attribute("value", BLE->getValue());

diff --git a/clang/lib/Basic/Targets/PPC.cpp b/clang/lib/Basic/Targets/PPC.cpp
@@ -93,6 +93,8 @@ bool PPCTargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasQuadwordAtomics = true;
     } else if (Feature == "+aix-shared-lib-tls-model-opt") {
       HasAIXShLibTLSModelOpt = true;
+    } else if (Feature == "+longcall") {
+      UseLongCalls = true;
     }
     // TODO: Finish this list and add an assert that we've handled them
     // all.
@@ -728,6 +730,7 @@ bool PPCTargetInfo::hasFeature(StringRef Feature) const {
       .Case("isa-v31-instructions", IsISA3_1)
       .Case("quadword-atomics", HasQuadwordAtomics)
       .Case("aix-shared-lib-tls-model-opt", HasAIXShLibTLSModelOpt)
+      .Case("longcall", UseLongCalls)
       .Default(false);
 }
 

diff --git a/clang/lib/Basic/Targets/PPC.h b/clang/lib/Basic/Targets/PPC.h
@@ -82,6 +82,7 @@ class LLVM_LIBRARY_VISIBILITY PPCTargetInfo : public TargetInfo {
   bool IsISA3_1 = false;
   bool HasQuadwordAtomics = false;
   bool HasAIXShLibTLSModelOpt = false;
+  bool UseLongCalls = false;
 
 protected:
   std::string ABI;

diff --git a/clang/lib/Basic/Targets/X86.cpp b/clang/lib/Basic/Targets/X86.cpp
@@ -457,6 +457,8 @@ bool X86TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
       HasCF = true;
     } else if (Feature == "+zu") {
       HasZU = true;
+    } else if (Feature == "+branch-hint") {
+      HasBranchHint = true;
     }
 
     X86SSEEnum Level = llvm::StringSwitch<X86SSEEnum>(Feature)
@@ -1292,6 +1294,7 @@ bool X86TargetInfo::hasFeature(StringRef Feature) const {
       .Case("nf", HasNF)
       .Case("cf", HasCF)
       .Case("zu", HasZU)
+      .Case("branch-hint", HasBranchHint)
       .Default(false);
 }
 

diff --git a/clang/lib/Basic/Targets/X86.h b/clang/lib/Basic/Targets/X86.h
@@ -174,6 +174,7 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
   bool HasCF = false;
   bool HasZU = false;
   bool HasInlineAsmUseGPR32 = false;
+  bool HasBranchHint = false;
 
 protected:
   llvm::X86::CPUKind CPU = llvm::X86::CK_None;

diff --git a/clang/lib/CodeGen/BackendConsumer.h b/clang/lib/CodeGen/BackendConsumer.h
@@ -107,7 +107,7 @@ class BackendConsumer : public ASTConsumer {
   void HandleTagDeclDefinition(TagDecl *D) override;
   void HandleTagDeclRequiredDefinition(const TagDecl *D) override;
   void CompleteTentativeDefinition(VarDecl *D) override;
-  void CompleteExternalDeclaration(VarDecl *D) override;
+  void CompleteExternalDeclaration(DeclaratorDecl *D) override;
   void AssignInheritanceModel(CXXRecordDecl *RD) override;
   void HandleVTable(CXXRecordDecl *RD) override;
 

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -5888,12 +5888,16 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_printf:
   case Builtin::BIprintf:
     if (getTarget().getTriple().isNVPTX() ||
-        getTarget().getTriple().isAMDGCN()) {
+        getTarget().getTriple().isAMDGCN() ||
+        (getTarget().getTriple().isSPIRV() &&
+         getTarget().getTriple().getVendor() == Triple::VendorType::AMD)) {
       if (getLangOpts().OpenMPIsTargetDevice)
         return EmitOpenMPDevicePrintfCallExpr(E);
       if (getTarget().getTriple().isNVPTX())
         return EmitNVPTXDevicePrintfCallExpr(E);
-      if (getTarget().getTriple().isAMDGCN() && getLangOpts().HIP)
+      if ((getTarget().getTriple().isAMDGCN() ||
+           getTarget().getTriple().isSPIRV()) &&
+          getLangOpts().HIP)
         return EmitAMDGPUDevicePrintfCallExpr(E);
     }
 

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
@@ -5751,8 +5751,35 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
   if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(CI)) {
     if (TargetDecl && TargetDecl->hasAttr<NotTailCalledAttr>())
       Call->setTailCallKind(llvm::CallInst::TCK_NoTail);
-    else if (IsMustTail)
+    else if (IsMustTail) {
+      if (getTarget().getTriple().isPPC()) {
+        if (getTarget().getTriple().isOSAIX())
+          CGM.getDiags().Report(Loc, diag::err_aix_musttail_unsupported);
+        else if (!getTarget().hasFeature("pcrelative-memops")) {
+          if (getTarget().hasFeature("longcall"))
+            CGM.getDiags().Report(Loc, diag::err_ppc_impossible_musttail) << 0;
+          else if (Call->isIndirectCall())
+            CGM.getDiags().Report(Loc, diag::err_ppc_impossible_musttail) << 1;
+          else if (isa_and_nonnull<FunctionDecl>(TargetDecl)) {
+            if (!cast<FunctionDecl>(TargetDecl)->isDefined())
+              // The undefined callee may be a forward declaration. Without
+              // knowning all symbols in the module, we won't know the symbol is
+              // defined or not. Collect all these symbols for later diagnosing.
+              CGM.addUndefinedGlobalForTailCall(
+                  {cast<FunctionDecl>(TargetDecl), Loc});
+            else {
+              llvm::GlobalValue::LinkageTypes Linkage = CGM.getFunctionLinkage(
+                  GlobalDecl(cast<FunctionDecl>(TargetDecl)));
+              if (llvm::GlobalValue::isWeakForLinker(Linkage) ||
+                  llvm::GlobalValue::isDiscardableIfUnused(Linkage))
+                CGM.getDiags().Report(Loc, diag::err_ppc_impossible_musttail)
+                    << 2;
+            }
+          }
+        }
+      }
       Call->setTailCallKind(llvm::CallInst::TCK_MustTail);
+    }
   }
 
   // Add metadata for calls to MSAllocator functions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
@@ -3141,21 +3141,8 @@ LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
     return LV;
   }
 
-  if (const auto *FD = dyn_cast<FunctionDecl>(ND)) {
-    LValue LV = EmitFunctionDeclLValue(*this, E, FD);
-
-    // Emit debuginfo for the function declaration if the target wants to.
-    if (getContext().getTargetInfo().allowDebugInfoForExternalRef()) {
-      if (CGDebugInfo *DI = CGM.getModuleDebugInfo()) {
-        auto *Fn =
-            cast<llvm::Function>(LV.getPointer(*this)->stripPointerCasts());
-        if (!Fn->getSubprogram())
-          DI->EmitFunctionDecl(FD, FD->getLocation(), T, Fn);
-      }
-    }
-
-    return LV;
-  }
+  if (const auto *FD = dyn_cast<FunctionDecl>(ND))
+    return EmitFunctionDeclLValue(*this, E, FD);
 
   // FIXME: While we're emitting a binding from an enclosing scope, all other
   // DeclRefExprs we see should be implicitly treated as if they also refer to

diff --git a/clang/lib/CodeGen/CGGPUBuiltin.cpp b/clang/lib/CodeGen/CGGPUBuiltin.cpp
@@ -179,7 +179,9 @@ RValue CodeGenFunction::EmitNVPTXDevicePrintfCallExpr(const CallExpr *E) {
 }
 
 RValue CodeGenFunction::EmitAMDGPUDevicePrintfCallExpr(const CallExpr *E) {
-  assert(getTarget().getTriple().getArch() == llvm::Triple::amdgcn);
+  assert(getTarget().getTriple().isAMDGCN() ||
+         (getTarget().getTriple().isSPIRV() &&
+          getTarget().getTriple().getVendor() == llvm::Triple::AMD));
   assert(E->getBuiltinCallee() == Builtin::BIprintf ||
          E->getBuiltinCallee() == Builtin::BI__builtin_printf);
   assert(E->getNumArgs() >= 1); // printf always has at least one arg.

diff --git a/clang/lib/CodeGen/CodeGenAction.cpp b/clang/lib/CodeGen/CodeGenAction.cpp
@@ -376,7 +376,7 @@ void BackendConsumer::CompleteTentativeDefinition(VarDecl *D) {
   Gen->CompleteTentativeDefinition(D);
 }
 
-void BackendConsumer::CompleteExternalDeclaration(VarDecl *D) {
+void BackendConsumer::CompleteExternalDeclaration(DeclaratorDecl *D) {
   Gen->CompleteExternalDeclaration(D);
 }
 

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1394,6 +1394,21 @@ void CodeGenModule::Release() {
   // that might affect the DLL storage class or the visibility, and
   // before anything that might act on these.
   setVisibilityFromDLLStorageClass(LangOpts, getModule());
+
+  // Check the tail call symbols are truly undefined.
+  if (getTriple().isPPC() && !MustTailCallUndefinedGlobals.empty()) {
+    for (auto &I : MustTailCallUndefinedGlobals) {
+      if (!I.first->isDefined())
+        getDiags().Report(I.second, diag::err_ppc_impossible_musttail) << 2;
+      else {
+        StringRef MangledName = getMangledName(GlobalDecl(I.first));
+        llvm::GlobalValue *Entry = GetGlobalValue(MangledName);
+        if (!Entry || Entry->isWeakForLinker() ||
+            Entry->isDeclarationForLinker())
+          getDiags().Report(I.second, diag::err_ppc_impossible_musttail) << 2;
+      }
+    }
+  }
 }
 
 void CodeGenModule::EmitOpenCLMetadata() {
@@ -5185,8 +5200,11 @@ void CodeGenModule::EmitTentativeDefinition(const VarDecl *D) {
   EmitGlobalVarDefinition(D);
 }
 
-void CodeGenModule::EmitExternalDeclaration(const VarDecl *D) {
-  EmitExternalVarDeclaration(D);
+void CodeGenModule::EmitExternalDeclaration(const DeclaratorDecl *D) {
+  if (auto const *V = dyn_cast<const VarDecl>(D))
+    EmitExternalVarDeclaration(V);
+  if (auto const *FD = dyn_cast<const FunctionDecl>(D))
+    EmitExternalFunctionDeclaration(FD);
 }
 
 CharUnits CodeGenModule::GetTargetTypeStoreSize(llvm::Type *Ty) const {
@@ -5622,6 +5640,18 @@ void CodeGenModule::EmitExternalVarDeclaration(const VarDecl *D) {
     }
 }
 
+void CodeGenModule::EmitExternalFunctionDeclaration(const FunctionDecl *FD) {
+  if (CGDebugInfo *DI = getModuleDebugInfo())
+    if (getCodeGenOpts().hasReducedDebugInfo()) {
+      auto *Ty = getTypes().ConvertType(FD->getType());
+      StringRef MangledName = getMangledName(FD);
+      auto *Fn = dyn_cast<llvm::Function>(
+          GetOrCreateLLVMFunction(MangledName, Ty, FD, /* ForVTable */ false));
+      if (!Fn->getSubprogram())
+        DI->EmitFunctionDecl(FD, FD->getLocation(), FD->getType(), Fn);
+    }
+}
+
 static bool isVarDeclStrongDefinition(const ASTContext &Context,
                                       CodeGenModule &CGM, const VarDecl *D,
                                       bool NoCommon) {

diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h
@@ -485,6 +485,14 @@ class CodeGenModule : public CodeGenTypeCache {
   typedef std::pair<OrderGlobalInitsOrStermFinalizers, llvm::Function *>
       GlobalInitData;
 
+  // When a tail call is performed on an "undefined" symbol, on PPC without pc
+  // relative feature, the tail call is not allowed. In "EmitCall" for such
+  // tail calls, the "undefined" symbols may be forward declarations, their
+  // definitions are provided in the module after the callsites. For such tail
+  // calls, diagnose message should not be emitted.
+  llvm::SmallSetVector<std::pair<const FunctionDecl *, SourceLocation>, 4>
+      MustTailCallUndefinedGlobals;
+
   struct GlobalInitPriorityCmp {
     bool operator()(const GlobalInitData &LHS,
                     const GlobalInitData &RHS) const {
@@ -1338,7 +1346,7 @@ class CodeGenModule : public CodeGenTypeCache {
 
   void EmitTentativeDefinition(const VarDecl *D);
 
-  void EmitExternalDeclaration(const VarDecl *D);
+  void EmitExternalDeclaration(const DeclaratorDecl *D);
 
   void EmitVTable(CXXRecordDecl *Class);
 
@@ -1647,6 +1655,11 @@ class CodeGenModule : public CodeGenTypeCache {
     return getTriple().isSPIRVLogical();
   }
 
+  void addUndefinedGlobalForTailCall(
+      std::pair<const FunctionDecl *, SourceLocation> Global) {
+    MustTailCallUndefinedGlobals.insert(Global);
+  }
+
 private:
   bool shouldDropDLLAttribute(const Decl *D, const llvm::GlobalValue *GV) const;
 
@@ -1690,6 +1703,7 @@ class CodeGenModule : public CodeGenTypeCache {
 
   void EmitGlobalVarDefinition(const VarDecl *D, bool IsTentative = false);
   void EmitExternalVarDeclaration(const VarDecl *D);
+  void EmitExternalFunctionDeclaration(const FunctionDecl *D);
   void EmitAliasDefinition(GlobalDecl GD);
   void emitIFuncDefinition(GlobalDecl GD);
   void emitCPUDispatchDefinition(GlobalDecl GD);

diff --git a/clang/lib/CodeGen/ModuleBuilder.cpp b/clang/lib/CodeGen/ModuleBuilder.cpp
@@ -310,7 +310,7 @@ namespace {
       Builder->EmitTentativeDefinition(D);
     }
 
-    void CompleteExternalDeclaration(VarDecl *D) override {
+    void CompleteExternalDeclaration(DeclaratorDecl *D) override {
       Builder->EmitExternalDeclaration(D);
     }
 

diff --git a/clang/lib/Driver/ToolChains/Darwin.cpp b/clang/lib/Driver/ToolChains/Darwin.cpp
@@ -3029,7 +3029,7 @@ void Darwin::addClangCC1ASTargetOptions(
       std::string Arg;
       llvm::raw_string_ostream OS(Arg);
       OS << "-target-sdk-version=" << V;
-      CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+      CC1ASArgs.push_back(Args.MakeArgString(Arg));
     };
 
     if (isTargetMacCatalyst()) {
@@ -3052,7 +3052,7 @@ void Darwin::addClangCC1ASTargetOptions(
         std::string Arg;
         llvm::raw_string_ostream OS(Arg);
         OS << "-darwin-target-variant-sdk-version=" << SDKInfo->getVersion();
-        CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+        CC1ASArgs.push_back(Args.MakeArgString(Arg));
       } else if (const auto *MacOStoMacCatalystMapping =
                      SDKInfo->getVersionMapping(
                          DarwinSDKInfo::OSEnvPair::macOStoMacCatalystPair())) {
@@ -3063,7 +3063,7 @@ void Darwin::addClangCC1ASTargetOptions(
           std::string Arg;
           llvm::raw_string_ostream OS(Arg);
           OS << "-darwin-target-variant-sdk-version=" << *SDKVersion;
-          CC1ASArgs.push_back(Args.MakeArgString(OS.str()));
+          CC1ASArgs.push_back(Args.MakeArgString(Arg));
         }
       }
     }

diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
@@ -3222,10 +3222,16 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
     if (Trimmed.contains(RawStringTermination))
       FormattingOff = false;
 
-    if (isClangFormatOff(Trimmed))
+    bool IsBlockComment = false;
+
+    if (isClangFormatOff(Trimmed)) {
       FormattingOff = true;
-    else if (isClangFormatOn(Trimmed))
+    } else if (isClangFormatOn(Trimmed)) {
       FormattingOff = false;
+    } else if (Trimmed.starts_with("/*")) {
+      IsBlockComment = true;
+      Pos = Code.find("*/", SearchFrom + 2);
+    }
 
     const bool EmptyLineSkipped =
         Trimmed.empty() &&
@@ -3235,9 +3241,10 @@ tooling::Replacements sortCppIncludes(const FormatStyle &Style, StringRef Code,
 
     bool MergeWithNextLine = Trimmed.ends_with("\\");
     if (!FormattingOff && !MergeWithNextLine) {
-      if (tooling::HeaderIncludes::IncludeRegex.match(Line, &Matches)) {
+      if (!IsBlockComment &&
+          tooling::HeaderIncludes::IncludeRegex.match(Trimmed, &Matches)) {
         StringRef IncludeName = Matches[2];
-        if (Line.contains("/*") && !Line.contains("*/")) {
+        if (Trimmed.contains("/*") && !Trimmed.contains("*/")) {
           // #include with a start of a block comment, but without the end.
           // Need to keep all the lines until the end of the comment together.
           // FIXME: This is somehow simplified check that probably does not work

diff --git a/clang/lib/Frontend/MultiplexConsumer.cpp b/clang/lib/Frontend/MultiplexConsumer.cpp
@@ -357,7 +357,7 @@ void MultiplexConsumer::CompleteTentativeDefinition(VarDecl *D) {
     Consumer->CompleteTentativeDefinition(D);
 }
 
-void MultiplexConsumer::CompleteExternalDeclaration(VarDecl *D) {
+void MultiplexConsumer::CompleteExternalDeclaration(DeclaratorDecl *D) {
   for (auto &Consumer : Consumers)
     Consumer->CompleteExternalDeclaration(D);
 }

diff --git a/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp b/clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp
@@ -273,10 +273,9 @@ namespace {
       std::string SStr;
       llvm::raw_string_ostream S(SStr);
       New->printPretty(S, nullptr, PrintingPolicy(LangOpts));
-      const std::string &Str = S.str();
 
       // If replacement succeeded or warning disabled return with no warning.
-      if (!Rewrite.ReplaceText(SrcRange.getBegin(), Size, Str)) {
+      if (!Rewrite.ReplaceText(SrcRange.getBegin(), Size, SStr)) {
         ReplacedNodes[Old] = New;
         return;
       }
@@ -2581,7 +2580,7 @@ Stmt *RewriteModernObjC::RewriteObjCStringLiteral(ObjCStringLiteral *Exp) {
   std::string prettyBufS;
   llvm::raw_string_ostream prettyBuf(prettyBufS);
   Exp->getString()->printPretty(prettyBuf, nullptr, PrintingPolicy(LangOpts));
-  Preamble += prettyBuf.str();
+  Preamble += prettyBufS;
   Preamble += ",";
   Preamble += utostr(Exp->getString()->getByteLength()) + "};\n";
 
@@ -4414,7 +4413,7 @@ void RewriteModernObjC::SynthesizeBlockLiterals(SourceLocation FunLocStart,
     llvm::raw_string_ostream constructorExprBuf(SStr);
     GlobalConstructionExp->printPretty(constructorExprBuf, nullptr,
                                        PrintingPolicy(LangOpts));
-    globalBuf += constructorExprBuf.str();
+    globalBuf += SStr;
     globalBuf += ";\n";
     InsertText(FunLocStart, globalBuf);
     GlobalConstructionExp = nullptr;

diff --git a/clang/lib/Interpreter/IncrementalParser.cpp b/clang/lib/Interpreter/IncrementalParser.cpp
@@ -79,7 +79,7 @@ class IncrementalASTConsumer final : public ASTConsumer {
   void CompleteTentativeDefinition(VarDecl *D) override final {
     Consumer->CompleteTentativeDefinition(D);
   }
-  void CompleteExternalDeclaration(VarDecl *D) override final {
+  void CompleteExternalDeclaration(DeclaratorDecl *D) override final {
     Consumer->CompleteExternalDeclaration(D);
   }
   void AssignInheritanceModel(CXXRecordDecl *RD) override final {

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -2117,8 +2117,6 @@ static void AddOverrideResults(ResultBuilder &Results,
         // Generates a new CodeCompletionResult by taking this function and
         // converting it into an override declaration with only one chunk in the
         // final CodeCompletionString as a TypedTextChunk.
-        std::string OverrideSignature;
-        llvm::raw_string_ostream OS(OverrideSignature);
         CodeCompletionResult CCR(Method, 0);
         PrintingPolicy Policy =
             getCompletionPrintingPolicy(S.getASTContext(), S.getPreprocessor());
@@ -3186,7 +3184,6 @@ static void AddTemplateParameterChunks(
       else if (const auto *TC = TTP->getTypeConstraint()) {
         llvm::raw_string_ostream OS(PlaceholderStr);
         TC->print(OS, Policy);
-        OS.flush();
       } else
         PlaceholderStr = "class";
 
@@ -4025,7 +4022,7 @@ CodeCompleteConsumer::OverloadCandidate::CreateSignatureString(
     std::string Name;
     llvm::raw_string_ostream OS(Name);
     FDecl->getDeclName().print(OS, Policy);
-    Result.AddTextChunk(Result.getAllocator().CopyString(OS.str()));
+    Result.AddTextChunk(Result.getAllocator().CopyString(Name));
   } else {
     // Function without a declaration. Just give the return type.
     Result.AddResultTypeChunk(Result.getAllocator().CopyString(
@@ -4343,7 +4340,7 @@ static void MaybeAddOverrideCalls(Sema &S, DeclContext *InContext,
         std::string Str;
         llvm::raw_string_ostream OS(Str);
         NNS->print(OS, Policy);
-        Builder.AddTextChunk(Results.getAllocator().CopyString(OS.str()));
+        Builder.AddTextChunk(Results.getAllocator().CopyString(Str));
       }
     } else if (!InContext->Equals(Overridden->getDeclContext()))
       continue;

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
@@ -10818,6 +10818,14 @@ Sema::ActOnFunctionDeclarator(Scope *S, Declarator &D, DeclContext *DC,
       break;
     }
 
+  // Similar to no_builtin logic above, at this point of the code
+  // FunctionDecl::isThisDeclarationADefinition() always returns `false`
+  // because Sema::ActOnStartOfFunctionDef has not been called yet.
+  if (Context.getTargetInfo().allowDebugInfoForExternalRef() &&
+      !NewFD->isInvalidDecl() &&
+      D.getFunctionDefinitionKind() == FunctionDefinitionKind::Declaration)
+    ExternalDeclarations.push_back(NewFD);
+
   return NewFD;
 }
 

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3719,8 +3719,11 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
       // The C++ standard bans deleting a pointer to a non-object type, which
       // effectively bans deletion of "void*". However, most compilers support
       // this, so we treat it as a warning unless we're in a SFINAE context.
-      Diag(StartLoc, diag::ext_delete_void_ptr_operand)
-        << Type << Ex.get()->getSourceRange();
+      // But we still prohibit this since C++26.
+      Diag(StartLoc, LangOpts.CPlusPlus26 ? diag::err_delete_incomplete
+                                          : diag::ext_delete_void_ptr_operand)
+          << (LangOpts.CPlusPlus26 ? Pointee : Type)
+          << Ex.get()->getSourceRange();
     } else if (Pointee->isFunctionType() || Pointee->isVoidType() ||
                Pointee->isSizelessType()) {
       return ExprError(Diag(StartLoc, diag::err_delete_operand)
@@ -3729,7 +3732,10 @@ Sema::ActOnCXXDelete(SourceLocation StartLoc, bool UseGlobal,
       // FIXME: This can result in errors if the definition was imported from a
       // module but is hidden.
       if (!RequireCompleteType(StartLoc, Pointee,
-                               diag::warn_delete_incomplete, Ex.get())) {
+                               LangOpts.CPlusPlus26
+                                   ? diag::err_delete_incomplete
+                                   : diag::warn_delete_incomplete,
+                               Ex.get())) {
         if (const RecordType *RT = PointeeElem->getAs<RecordType>())
           PointeeRD = cast<CXXRecordDecl>(RT->getDecl());
       }

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
@@ -9811,9 +9811,6 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
     // C++ [over.best.ics]p4:
     //   When [...] the constructor [...] is a candidate by
     //    - [over.match.copy] (in all cases)
-    // FIXME: The "second phase of [over.match.list] case can also
-    // theoretically happen here, but it's not clear whether we can
-    // ever have a parameter of the right type.
     if (TD) {
       SmallVector<Expr *, 8> TmpInits;
       for (Expr *E : Inits)

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4704,6 +4704,12 @@ void Sema::InstantiateExceptionSpec(SourceLocation PointOfInstantiation,
     return;
   }
 
+  // The noexcept specification could reference any lambda captures. Ensure
+  // those are added to the LocalInstantiationScope.
+  LambdaScopeForCallOperatorInstantiationRAII PushLambdaCaptures(
+      *this, Decl, TemplateArgs, Scope,
+      /*ShouldAddDeclsFromParentScope=*/false);
+
   SubstExceptionSpec(Decl, Template->getType()->castAs<FunctionProtoType>(),
                      TemplateArgs);
 }

diff --git a/clang/test/AST/Interp/records.cpp b/clang/test/AST/Interp/records.cpp
@@ -494,6 +494,12 @@ namespace DeclRefs {
   constexpr B b;
   static_assert(b.a.m == 100, "");
   static_assert(b.a.f == 100, "");
+
+  constexpr B b2;
+  static_assert(b2.a.m == 100, "");
+  static_assert(b2.a.f == 100, "");
+  static_assert(b2.a.f == 101, ""); // both-error {{failed}} \
+                                    // both-note {{evaluates to '100 == 101'}}
 }
 
 namespace PointerArith {

diff --git a/clang/test/CXX/drs/cwg5xx.cpp b/clang/test/CXX/drs/cwg5xx.cpp
@@ -1,9 +1,10 @@
-// RUN: %clang_cc1 -std=c++98 %s -verify=expected,cxx98-11,cxx98-14,cxx98-17,cxx98 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 %s -verify=expected,cxx98-11,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 %s -verify=expected,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++17 %s -verify=expected,since-cxx17,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++20 %s -verify=expected,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++23 %s -verify=expected,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 %s -verify=expected,cxx98-23,cxx98-11,cxx98-14,cxx98-17,cxx98 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 %s -verify=expected,cxx98-23,cxx98-11,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 %s -verify=expected,cxx98-23,cxx98-14,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 %s -verify=expected,cxx98-23,since-cxx17,cxx98-17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 %s -verify=expected,cxx98-23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++23 %s -verify=expected,cxx98-23,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c %s -verify=expected,since-cxx26,since-cxx23,since-cxx20,since-cxx17,since-cxx11 -fexceptions -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus == 199711L
 #define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
@@ -901,7 +902,8 @@ namespace cwg573 { // cwg573: no
   void *d = reinterpret_cast<void*>(c);
   // cxx98-error@-1 {{cast between pointer-to-function and pointer-to-object is an extension}}
   void f() { delete a; }
-  // expected-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+  // cxx98-23-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+  // since-cxx26-error@-2 {{cannot delete pointer to incomplete type 'void'}}
   int n = d - a;
   // expected-error@-1 {{arithmetic on pointers to void}}
   // FIXME: This is ill-formed.
@@ -1238,11 +1240,13 @@ namespace cwg599 { // cwg599: partial
   struct V { operator int*(); operator Fn*(); };
   void f(void *p, void (*q)(), S s, T t, U u, V v) {
     delete p;
-    // expected-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+    // cxx98-23-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+    // since-cxx26-error@-2 {{cannot delete pointer to incomplete type 'void'}}
     delete q;
     // expected-error@-1 {{cannot delete expression of type 'void (*)()'}}
     delete s;
-    // expected-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+    // cxx98-23-error@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+    // since-cxx26-error@-2 {{cannot delete pointer to incomplete type 'void'}}
     delete t;
     // expected-error@-1 {{cannot delete expression of type 'T'}}
     // FIXME: This is valid, but is rejected due to a non-conforming GNU

diff --git a/clang/test/CodeGen/PowerPC/musttail-forward-declaration-inline.c b/clang/test/CodeGen/PowerPC/musttail-forward-declaration-inline.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+
+inline int func2(int i);
+int external_call2(int i) {
+  // expected-error@+1 {{'musttail' attribute for this call is impossible because external calls can not be tail called on PPC}}
+  [[clang::musttail]] return func2(i);
+}
+
+inline int func2(int i) {
+  return 0;
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-forward-declaration-weak.c b/clang/test/CodeGen/PowerPC/musttail-forward-declaration-weak.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+
+int func2(int i);
+int external_call2(int i) {
+  // expected-error@+1 {{'musttail' attribute for this call is impossible because external calls can not be tail called on PPC}}
+  [[clang::musttail]] return func2(i);
+}
+
+__attribute__((weak)) int func2(int i) {
+  return 0;
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-forward-declaration.c b/clang/test/CodeGen/PowerPC/musttail-forward-declaration.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify=good
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify=good
+
+int func2(int i);
+int external_call2(int i) {
+  // good-no-diagnostics
+  [[clang::musttail]] return func2(i);
+}
+int func2(int i) {
+  return 0;
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-indirect.cpp b/clang/test/CodeGen/PowerPC/musttail-indirect.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+// RUN: %clang_cc1 %s -triple powerpc-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+
+void name(int *params) {
+  auto fn = (void (*)(int *))1;
+  // expected-error@+1 {{'musttail' attribute for this call is impossible because indirect calls can not be tail called on PPC}}
+  [[clang::musttail]] return fn(params);
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-inline.c b/clang/test/CodeGen/PowerPC/musttail-inline.c
@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+
+inline int foo(int x) {
+  return x;
+}
+
+int bar(int x)
+{
+  // expected-error@+1 {{'musttail' attribute for this call is impossible because external calls can not be tail called on PPC}}
+  [[clang::musttail]] return foo(1);
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-undefined.c b/clang/test/CodeGen/PowerPC/musttail-undefined.c
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify
+
+int foo(int x);
+
+int bar(int x)
+{
+  // expected-error@+1 {{'musttail' attribute for this call is impossible because external calls can not be tail called on PPC}}
+  [[clang::musttail]] return foo(x);
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail-weak.c b/clang/test/CodeGen/PowerPC/musttail-weak.c
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 %s -triple powerpc64-ibm-aix-xcoff -o /dev/null -emit-llvm -verify=aix
+// RUN: %clang_cc1 %s -triple powerpc-ibm-aix-xcoff -o /dev/null -emit-llvm -verify=aix
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify=linux
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify=linux
+
+__attribute__((weak)) int func2(int i) {
+  return 0;
+}
+int external_call2(int i) {
+  // linux-error@+2 {{'musttail' attribute for this call is impossible because external calls can not be tail called on PPC}}
+  // aix-error@+1 {{'musttail' attribute is not supported on AIX}}
+  [[clang::musttail]] return func2(i);
+}
diff --git a/clang/test/CodeGen/PowerPC/musttail.c b/clang/test/CodeGen/PowerPC/musttail.c
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 %s -triple powerpc64-ibm-aix-xcoff -o /dev/null -emit-llvm -verify=aix
+// RUN: %clang_cc1 %s -triple powerpc-ibm-aix-xcoff -o /dev/null -emit-llvm -verify=aix
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-linux-gnu -o /dev/null -emit-llvm -verify=good
+// RUN: %clang_cc1 %s -triple powerpc-unknown-linux-gnu -o /dev/null -emit-llvm -verify=good
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -o /dev/null -emit-llvm -verify=good
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -target-feature +pcrelative-memops -o /dev/null -emit-llvm -verify=good
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -target-feature +longcall -o /dev/null -emit-llvm -verify=longcall
+// RUN: %clang_cc1 %s -triple powerpc64le-unknown-linux-gnu -target-feature +pcrelative-memops -target-feature +longcall -o /dev/null -emit-llvm -verify=good
+
+int foo(int x) {
+  return x;
+}
+
+int bar(int x)
+{
+  // good-no-diagnostics
+  // longcall-error@+2 {{'musttail' attribute for this call is impossible because long calls can not be tail called on PPC}}
+  // aix-error@+1 {{'musttail' attribute is not supported on AIX}}
+ [[clang::musttail]] return foo(1);
+}
diff --git a/clang/test/CodeGen/bpf-debug-info-extern-func.c b/clang/test/CodeGen/bpf-debug-info-extern-func.c
@@ -0,0 +1,9 @@
+// RUN: %clang -g -target bpf -S -emit-llvm %s -o - | FileCheck %s
+//
+// When linking BPF object files via bpftool, BTF info is required for
+// every symbol. BTF is generated from debug info. Ensure that debug info
+// is emitted for extern functions referenced via variable initializers.
+//
+// CHECK: !DISubprogram(name: "fn"
+extern void fn(void);
+void (*pfn) (void) = &fn;
diff --git a/clang/test/CodeGen/bpf-debug-info-unref.c b/clang/test/CodeGen/bpf-debug-info-unref.c
@@ -0,0 +1,11 @@
+// RUN: %clang -g -target bpf -S -emit-llvm %s -o - | FileCheck %s
+//
+// No debug info is produced for unreferenced functions.
+// CHECK-NOT: !DISubprogram
+void unref(void);
+void unref2(typeof(unref));
+
+// No debug info for unused extern variables as well.
+// CHECK-NOT: !DiGlobalVariable
+extern int unused;
+extern int unused2[sizeof(unused)];
diff --git a/clang/test/CodeGenHIP/printf-builtin.hip b/clang/test/CodeGenHIP/printf-builtin.hip
@@ -1,8 +1,12 @@
 // REQUIRES: amdgpu-registered-target
 // RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -emit-llvm -disable-llvm-optzns -mprintf-kind=hostcall -fno-builtin-printf -fcuda-is-device \
 // RUN:   -o - %s | FileCheck --check-prefixes=CHECK,HOSTCALL %s
+// RUN: %clang_cc1 -triple spirv64-amd-amdhsa -emit-llvm -disable-llvm-optzns -mprintf-kind=hostcall -fno-builtin-printf -fcuda-is-device \
+// RUN:   -o - %s | FileCheck --check-prefixes=CHECK-AMDGCNSPIRV,HOSTCALL-AMDGCNSPIRV %s
 // RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -emit-llvm -disable-llvm-optzns -mprintf-kind=buffered -fno-builtin-printf -fcuda-is-device \
 // RUN:   -o - %s | FileCheck --check-prefixes=CHECK,BUFFERED %s
+// RUN: %clang_cc1 -triple spirv64-amd-amdhsa -emit-llvm -disable-llvm-optzns -mprintf-kind=buffered -fno-builtin-printf -fcuda-is-device \
+// RUN:   -o - %s | FileCheck --check-prefixes=CHECK-AMDGCNSPIRV,BUFFERED-AMDGCNSPIRV %s
 
 #define __device__ __attribute__((device))
 
@@ -11,13 +15,17 @@ extern "C" __device__ int printf(const char *format, ...);
 // CHECK-LABEL: @_Z4foo1v()
 __device__ int foo1() {
   // HOSTCALL: call i64 @__ockl_printf_begin
+  // HOSTCALL-AMDGCNSPIRV: call addrspace(4) i64 @__ockl_printf_begin
   // BUFFERED: call ptr addrspace(1) @__printf_alloc
+  // BUFFERED-AMDGCNSPIRV: call addrspace(4) ptr addrspace(1) @__printf_alloc
   // CHECK-NOT: call i32 (ptr, ...) @printf
+  // CHECK-AMDGCNSPIRV-NOT: call i32 (ptr, ...) @printf
   return __builtin_printf("Hello World\n");
 }
 
 // CHECK-LABEL: @_Z4foo2v()
 __device__ int foo2() {
   // CHECK: call i32 (ptr, ...) @printf
+  // CHECK-AMDGCNSPIRV: call spir_func addrspace(4) i32 (ptr addrspace(4), ...) @printf
   return printf("Hello World\n");
 }
diff --git a/clang/test/CodeGenHIP/printf.cpp b/clang/test/CodeGenHIP/printf.cpp
diff --git a/clang/test/OpenMP/deferred-diags.cpp b/clang/test/OpenMP/deferred-diags.cpp
@@ -41,7 +41,7 @@ namespace TestDeleteIncompleteClassDefinition {
 struct a;
 struct b {
   b() {
-    delete c; // expected-warning {{deleting pointer to incomplete type 'a' may cause undefined behavior}}
+    delete c; // expected-warning {{deleting pointer to incomplete type 'a' is incompatible with C++2c and may cause undefined behavior}}
   }
   a *c;
 };

diff --git a/clang/test/SemaCXX/eval-crashes.cpp b/clang/test/SemaCXX/eval-crashes.cpp
@@ -61,3 +61,13 @@ struct array {
   array() : data(*new int[1][2]) {}
 };
 }
+
+namespace GH96670 {
+inline constexpr long ullNil = -1;
+
+template<typename T = long, const T &Nil = ullNil>
+struct Test {};
+
+inline constexpr long lNil = -1;
+Test<long, lNil> c;
+}
diff --git a/clang/test/SemaCXX/new-delete.cpp b/clang/test/SemaCXX/new-delete.cpp
@@ -1,8 +1,10 @@
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++98
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++11
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++14
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx17,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++17
-// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++20
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++98
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++11
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++14
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,precxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++17
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++20
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,cxx98-23,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++23
+// RUN: %clang_cc1 -fsyntax-only -verify=expected,since-cxx26,cxx17,cxx20 %s -triple=i686-pc-linux-gnu -Wno-new-returns-null -std=c++2c
 
 // FIXME Location is (frontend)
 // cxx17-note@*:* {{candidate function not viable: requires 2 arguments, but 3 were provided}}
@@ -172,8 +174,12 @@ void bad_deletes()
 {
   delete 0; // expected-error {{cannot delete expression of type 'int'}}
   delete [0] (int*)0; // expected-error {{expected variable name or 'this' in lambda capture list}}
-  delete (void*)0; // expected-warning {{cannot delete expression with pointer-to-'void' type 'void *'}}
-  delete (T*)0; // expected-warning {{deleting pointer to incomplete type}}
+  delete (void*)0;
+  // cxx98-23-warning@-1 {{cannot delete expression with pointer-to-'void' type 'void *'}}
+  // since-cxx26-error@-2 {{cannot delete pointer to incomplete type 'void'}}
+  delete (T*)0;
+  // cxx98-23-warning@-1 {{deleting pointer to incomplete type}}
+  // since-cxx26-error@-2 {{cannot delete pointer to incomplete type 'T'}}
   ::S::delete (int*)0; // expected-error {{expected unqualified-id}}
 }
 
@@ -513,8 +519,10 @@ namespace DeleteIncompleteClass {
 
 namespace DeleteIncompleteClassPointerError {
   struct A; // expected-note {{forward declaration}}
-  void f(A *x) { 1+delete x; } // expected-warning {{deleting pointer to incomplete type}} \
-                               // expected-error {{invalid operands to binary expression}}
+  void f(A *x) { 1+delete x; }
+  // expected-error@-1 {{invalid operands to binary expression}}
+  // cxx98-23-warning@-2 {{deleting pointer to incomplete type}}
+  // since-cxx26-error@-3 {{cannot delete pointer to incomplete type 'A'}}
 }
 
 namespace PR10504 {

diff --git a/clang/test/SemaTemplate/generic-lambda.cpp b/clang/test/SemaTemplate/generic-lambda.cpp
@@ -60,3 +60,26 @@ template<class T1> C1<X<X<T1>>> auto t3() {
 template C1<X<X<int>>> auto t3<int>();
 static_assert(is_same<decltype(t3<int>()), X<X<X<int>>>>);
 #endif
+
+namespace GH95735 {
+
+int g(int fn) {
+  return [f = fn](auto tpl) noexcept(noexcept(f)) { return f; }(0);
+}
+
+int foo(auto... fn) {
+  // FIXME: This one hits the assertion "if the exception specification is dependent,
+  // then the noexcept expression should be value-dependent" in the constructor of
+  // FunctionProtoType.
+  // One possible solution is to update Sema::canThrow() to consider expressions
+  // (e.g. DeclRefExpr/FunctionParmPackExpr) involving unexpanded parameters as Dependent.
+  // This would effectively add an extra value-dependent flag to the noexcept expression.
+  // However, I'm afraid that would also cause ABI breakage.
+  // [...f = fn](auto tpl) noexcept(noexcept(f)) { return 0; }(0);
+  [...f = fn](auto tpl) noexcept(noexcept(g(fn...))) { return 0; }(0);
+  return [...f = fn](auto tpl) noexcept(noexcept(g(f...))) { return 0; }(0);
+}
+
+int v = foo(42);
+
+} // namespace GH95735
diff --git a/clang/unittests/Format/SortIncludesTest.cpp b/clang/unittests/Format/SortIncludesTest.cpp
@@ -1455,6 +1455,15 @@ TEST_F(SortIncludesTest, DisableRawStringLiteralSorting) {
 #undef X
 }
 
+TEST_F(SortIncludesTest, BlockCommentedOutIncludes) {
+  StringRef Code{"/* #include \"foo.h\"\n"
+                 "#include \"bar.h\" */\n"
+                 "#include <chrono>"};
+
+  FmtStyle = getGoogleStyle(FormatStyle::LK_Cpp);
+  verifyFormat(Code, sort(Code, "input.cpp", 0));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang
diff --git a/clang/www/cxx_status.html b/clang/www/cxx_status.html
@@ -213,7 +213,7 @@ <h2 id="cxx26">C++2c implementation status</h2>
  <tr>
   <td>Deleting a Pointer to an Incomplete Type Should be Ill-formed</td>
   <td><a href="https://wg21.link/P3144">P3144R2</a></td>
-  <td class="none" align="center">No</td>
+  <td class="unreleased" align="center">Clang 19</td>
  </tr>
  <tr>
   <td>Ordering of constraints involving fold expressions</td>

diff --git a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
@@ -368,14 +368,23 @@ macro(construct_compiler_rt_default_triple)
           "Default triple for which compiler-rt runtimes will be built.")
   endif()
 
-  if ("${CMAKE_C_COMPILER_ID}" MATCHES "Clang")
+  if(CMAKE_C_COMPILER_ID MATCHES "Clang")
     set(option_prefix "")
     if (CMAKE_C_SIMULATE_ID MATCHES "MSVC")
       set(option_prefix "/clang:")
     endif()
-    execute_process(COMMAND ${CMAKE_C_COMPILER} ${option_prefix}--target=${COMPILER_RT_DEFAULT_TARGET_TRIPLE} ${option_prefix}-print-target-triple
-                    OUTPUT_VARIABLE COMPILER_RT_DEFAULT_TARGET_TRIPLE
-                    OUTPUT_STRIP_TRAILING_WHITESPACE)
+    set(print_target_triple ${CMAKE_C_COMPILER} ${option_prefix}--target=${COMPILER_RT_DEFAULT_TARGET_TRIPLE} ${option_prefix}-print-target-triple)
+    execute_process(COMMAND ${print_target_triple}
+      RESULT_VARIABLE result
+      OUTPUT_VARIABLE output
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    if(result EQUAL 0)
+      set(COMPILER_RT_DEFAULT_TARGET_TRIPLE ${output})
+    else()
+      string(REPLACE ";" " " print_target_triple "${print_target_triple}")
+      # TODO(#97876): Report an error.
+      message(WARNING "Failed to execute `${print_target_triple}` to normalize target triple.")
+    endif()
   endif()
 
   string(REPLACE "-" ";" LLVM_TARGET_TRIPLE_LIST ${COMPILER_RT_DEFAULT_TARGET_TRIPLE})

diff --git a/compiler-rt/include/orc_rt/c_api.h b/compiler-rt/include/orc_rt/c_api.h
@@ -72,9 +72,6 @@ typedef struct {
   size_t Size;
 } orc_rt_CWrapperFunctionResult;
 
-typedef struct orc_rt_CSharedOpaqueJITProcessControl
-    *orc_rt_SharedJITProcessControlRef;
-
 /**
  * Zero-initialize an orc_rt_CWrapperFunctionResult.
  */

diff --git a/compiler-rt/lib/builtins/cpu_model/AArch64CPUFeatures.inc b/compiler-rt/lib/builtins/cpu_model/AArch64CPUFeatures.inc
@@ -0,0 +1,91 @@
+//===- AArch64CPUFeatures.inc - AArch64 CPU Features enum -------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the CPUFeatures enum for AArch64 to facilitate better
+// testing of this code between LLVM and compiler-rt, primarily that the files
+// are an exact match.
+//
+// This file has two identical copies. The primary copy lives in LLVM and
+// the other one sits in compiler-rt/lib/builtins/cpu_model directory. To make
+// changes in this file, first modify the primary copy and copy it over to
+// compiler-rt. compiler-rt tests will fail if the two files are not synced up.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef AARCH64_CPU_FEATURS_INC_H
+#define AARCH64_CPU_FEATURS_INC_H
+
+// Function Multi Versioning CPU features.
+enum CPUFeatures {
+  FEAT_RNG,
+  FEAT_FLAGM,
+  FEAT_FLAGM2,
+  FEAT_FP16FML,
+  FEAT_DOTPROD,
+  FEAT_SM4,
+  FEAT_RDM,
+  FEAT_LSE,
+  FEAT_FP,
+  FEAT_SIMD,
+  FEAT_CRC,
+  FEAT_SHA1,
+  FEAT_SHA2,
+  FEAT_SHA3,
+  FEAT_AES,
+  FEAT_PMULL,
+  FEAT_FP16,
+  FEAT_DIT,
+  FEAT_DPB,
+  FEAT_DPB2,
+  FEAT_JSCVT,
+  FEAT_FCMA,
+  FEAT_RCPC,
+  FEAT_RCPC2,
+  FEAT_FRINTTS,
+  FEAT_DGH,
+  FEAT_I8MM,
+  FEAT_BF16,
+  FEAT_EBF16,
+  FEAT_RPRES,
+  FEAT_SVE,
+  FEAT_SVE_BF16,
+  FEAT_SVE_EBF16,
+  FEAT_SVE_I8MM,
+  FEAT_SVE_F32MM,
+  FEAT_SVE_F64MM,
+  FEAT_SVE2,
+  FEAT_SVE_AES,
+  FEAT_SVE_PMULL128,
+  FEAT_SVE_BITPERM,
+  FEAT_SVE_SHA3,
+  FEAT_SVE_SM4,
+  FEAT_SME,
+  FEAT_MEMTAG,
+  FEAT_MEMTAG2,
+  FEAT_MEMTAG3,
+  FEAT_SB,
+  FEAT_PREDRES,
+  FEAT_SSBS,
+  FEAT_SSBS2,
+  FEAT_BTI,
+  FEAT_LS64,
+  FEAT_LS64_V,
+  FEAT_LS64_ACCDATA,
+  FEAT_WFXT,
+  FEAT_SME_F64,
+  FEAT_SME_I64,
+  FEAT_SME2,
+  FEAT_RCPC3,
+  FEAT_MOPS,
+  FEAT_MAX,
+  FEAT_EXT = 62, // Reserved to indicate presence of additional features field
+                 // in __aarch64_cpu_features
+  FEAT_INIT      // Used as flag of features initialization completion
+};
+
+#endif
diff --git a/compiler-rt/lib/builtins/cpu_model/aarch64.h b/compiler-rt/lib/builtins/cpu_model/aarch64.h
@@ -14,74 +14,7 @@
 
 #if !defined(DISABLE_AARCH64_FMV)
 
-// CPUFeatures must correspond to the same AArch64 features in
-// AArch64TargetParser.h
-enum CPUFeatures {
-  FEAT_RNG,
-  FEAT_FLAGM,
-  FEAT_FLAGM2,
-  FEAT_FP16FML,
-  FEAT_DOTPROD,
-  FEAT_SM4,
-  FEAT_RDM,
-  FEAT_LSE,
-  FEAT_FP,
-  FEAT_SIMD,
-  FEAT_CRC,
-  FEAT_SHA1,
-  FEAT_SHA2,
-  FEAT_SHA3,
-  FEAT_AES,
-  FEAT_PMULL,
-  FEAT_FP16,
-  FEAT_DIT,
-  FEAT_DPB,
-  FEAT_DPB2,
-  FEAT_JSCVT,
-  FEAT_FCMA,
-  FEAT_RCPC,
-  FEAT_RCPC2,
-  FEAT_FRINTTS,
-  FEAT_DGH,
-  FEAT_I8MM,
-  FEAT_BF16,
-  FEAT_EBF16,
-  FEAT_RPRES,
-  FEAT_SVE,
-  FEAT_SVE_BF16,
-  FEAT_SVE_EBF16,
-  FEAT_SVE_I8MM,
-  FEAT_SVE_F32MM,
-  FEAT_SVE_F64MM,
-  FEAT_SVE2,
-  FEAT_SVE_AES,
-  FEAT_SVE_PMULL128,
-  FEAT_SVE_BITPERM,
-  FEAT_SVE_SHA3,
-  FEAT_SVE_SM4,
-  FEAT_SME,
-  FEAT_MEMTAG,
-  FEAT_MEMTAG2,
-  FEAT_MEMTAG3,
-  FEAT_SB,
-  FEAT_PREDRES,
-  FEAT_SSBS,
-  FEAT_SSBS2,
-  FEAT_BTI,
-  FEAT_LS64,
-  FEAT_LS64_V,
-  FEAT_LS64_ACCDATA,
-  FEAT_WFXT,
-  FEAT_SME_F64,
-  FEAT_SME_I64,
-  FEAT_SME2,
-  FEAT_RCPC3,
-  FEAT_MOPS,
-  FEAT_MAX,
-  FEAT_EXT = 62, // Reserved to indicate presence of additional features field
-                 // in __aarch64_cpu_features
-  FEAT_INIT      // Used as flag of features initialization completion
-};
+#include "AArch64CPUFeatures.inc"
 
 void __init_cpu_features(void);
 

diff --git a/compiler-rt/lib/orc/error.h b/compiler-rt/lib/orc/error.h
@@ -1,4 +1,4 @@
-//===-------- Error.h - Enforced error checking for ORC RT ------*- C++ -*-===//
+//===-------- error.h - Enforced error checking for ORC RT ------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.

diff --git a/compiler-rt/test/builtins/TestCases/check-same-common-code.test b/compiler-rt/test/builtins/TestCases/check-same-common-code.test
@@ -0,0 +1,5 @@
+;
+; NOTE: if this test fails, please make sure the relevant copies are identical
+; copies of each other.
+;
+; RUN: diff %crt_src/lib/builtins/cpu_model/AArch64CPUFeatures.inc %llvm_src/include/llvm/TargetParser/AArch64CPUFeatures.inc
diff --git a/compiler-rt/test/builtins/lit.cfg.py b/compiler-rt/test/builtins/lit.cfg.py
@@ -9,7 +9,7 @@
 config.test_source_root = os.path.dirname(__file__)
 
 # Test suffixes.
-config.suffixes = [".c", ".cpp", ".m", ".mm"]
+config.suffixes = [".c", ".cpp", ".m", ".mm", ".test"]
 extra_flags = ["-Wall"]
 if config.compiler_id == "GNU":
     # detect incorrect declarations of libgcc functions

diff --git a/compiler-rt/test/profile/check-same-common-code.test b/compiler-rt/test/profile/check-same-common-code.test
@@ -0,0 +1,7 @@
+;
+; NOTE: if this test fails, please make sure the files are identical
+; copies of each other.
+;
+; RUN: diff %crt_src/include/profile/MIBEntryDef.inc %llvm_src/include/llvm/ProfileData/MIBEntryDef.inc
+; RUN: diff %crt_src/include/profile/MemProfData.inc %llvm_src/include/llvm/ProfileData/MemProfData.inc
+; RUN: diff %crt_src/include/profile/InstrProfData.inc %llvm_src/include/llvm/ProfileData/InstrProfData.inc
diff --git a/libc/benchmarks/gpu/LibcGpuBenchmark.cpp b/libc/benchmarks/gpu/LibcGpuBenchmark.cpp
@@ -17,7 +17,8 @@ void Benchmark::add_benchmark(Benchmark *benchmark) {
   benchmarks.push_back(benchmark);
 }
 
-BenchmarkResult reduce_results(cpp::array<BenchmarkResult, 1024> &results) {
+BenchmarkResult
+reduce_results(const cpp::array<BenchmarkResult, 1024> &results) {
   BenchmarkResult result;
   uint64_t cycles_sum = 0;
   double standard_deviation_sum = 0;
@@ -51,16 +52,16 @@ void Benchmark::run_benchmarks() {
   uint64_t id = gpu::get_thread_id();
   gpu::sync_threads();
 
-  for (Benchmark *benchmark : benchmarks)
-    results[id] = benchmark->run();
+  for (Benchmark *b : benchmarks)
+    results[id] = b->run();
   gpu::sync_threads();
   if (id == 0) {
-    for (Benchmark *benchmark : benchmarks) {
+    for (Benchmark const *b : benchmarks) {
       BenchmarkResult all_results = reduce_results(results);
       constexpr auto GREEN = "\033[32m";
       constexpr auto RESET = "\033[0m";
-      log << GREEN << "[ RUN      ] " << RESET << benchmark->get_name() << '\n';
-      log << GREEN << "[       OK ] " << RESET << benchmark->get_name() << ": "
+      log << GREEN << "[ RUN      ] " << RESET << b->get_name() << '\n';
+      log << GREEN << "[       OK ] " << RESET << b->get_name() << ": "
           << all_results.cycles << " cycles, " << all_results.min << " min, "
           << all_results.max << " max, " << all_results.total_iterations
           << " iterations, " << all_results.total_time << " ns, "
@@ -82,7 +83,6 @@ BenchmarkResult benchmark(const BenchmarkOptions &options,
   uint32_t samples = 0;
   uint64_t total_time = 0;
   uint64_t best_guess = 0;
-  uint64_t total_cycles = 0;
   uint64_t cycles_squared = 0;
   uint64_t min = UINT64_MAX;
   uint64_t max = 0;
@@ -92,23 +92,22 @@ BenchmarkResult benchmark(const BenchmarkOptions &options,
   for (int i = 0; i < overhead_iterations; i++)
     overhead = cpp::min(overhead, LIBC_NAMESPACE::overhead());
 
-  for (uint64_t time_budget = options.max_duration; time_budget >= 0;) {
+  for (int64_t time_budget = options.max_duration; time_budget >= 0;) {
     uint64_t sample_cycles = 0;
     const clock_t start = static_cast<double>(clock());
     for (uint32_t i = 0; i < iterations; i++) {
       auto wrapper_intermediate = wrapper_func();
-      uint64_t result = wrapper_intermediate - overhead;
-      max = cpp::max(max, result);
-      min = cpp::min(min, result);
-      sample_cycles += result;
+      uint64_t current_result = wrapper_intermediate - overhead;
+      max = cpp::max(max, current_result);
+      min = cpp::min(min, current_result);
+      sample_cycles += current_result;
     }
     const clock_t end = clock();
     const clock_t duration_ns =
         ((end - start) * 1000 * 1000 * 1000) / CLOCKS_PER_SEC;
     total_time += duration_ns;
     time_budget -= duration_ns;
     samples++;
-    total_cycles += sample_cycles;
     cycles_squared += sample_cycles * sample_cycles;
 
     total_iterations += iterations;

diff --git a/libc/benchmarks/gpu/LibcGpuBenchmark.h b/libc/benchmarks/gpu/LibcGpuBenchmark.h
@@ -19,8 +19,8 @@ struct BenchmarkOptions {
   uint32_t max_iterations = 10000000;
   uint32_t min_samples = 4;
   uint32_t max_samples = 1000;
-  uint64_t min_duration = 0;                  // in nanoseconds (ns)
-  uint64_t max_duration = 1000 * 1000 * 1000; // 1e9 nanoseconds = 1 second
+  int64_t min_duration = 0;                  // in nanoseconds (ns)
+  int64_t max_duration = 1000 * 1000 * 1000; // 1e9 nanoseconds = 1 second
   double epsilon = 0.01;
   double scaling_factor = 1.4;
 };

diff --git a/libc/config/baremetal/arm/entrypoints.txt b/libc/config/baremetal/arm/entrypoints.txt
@@ -386,6 +386,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.sqrt
     libc.src.math.sqrtf
     libc.src.math.sqrtl
+    libc.src.math.tan
     libc.src.math.tanf
     libc.src.math.tanhf
     libc.src.math.trunc

diff --git a/libc/config/baremetal/riscv/entrypoints.txt b/libc/config/baremetal/riscv/entrypoints.txt
@@ -381,6 +381,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.sqrt
     libc.src.math.sqrtf
     libc.src.math.sqrtl
+    libc.src.math.tan
     libc.src.math.tanf
     libc.src.math.tanhf
     libc.src.math.trunc

diff --git a/libc/config/darwin/arm/entrypoints.txt b/libc/config/darwin/arm/entrypoints.txt
@@ -132,6 +132,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.coshf
     libc.src.math.cos
     libc.src.math.cosf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.expf

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
@@ -17,6 +17,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
+    # dlfcn.h entrypoints
+    libc.src.dlfcn.dlclose
+    libc.src.dlfcn.dlerror
+    libc.src.dlfcn.dlopen
+    libc.src.dlfcn.dlsym
+
     # errno.h entrypoints
     libc.src.errno.errno
 
@@ -284,6 +290,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -295,6 +302,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read
@@ -346,6 +354,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10

diff --git a/libc/config/linux/aarch64/headers.txt b/libc/config/linux/aarch64/headers.txt
@@ -1,6 +1,7 @@
 set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
+    libc.include.dlfcn
     libc.include.errno
     libc.include.features
     libc.include.fenv

diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
@@ -289,6 +289,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -300,6 +301,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pread
     libc.src.unistd.pwrite
     libc.src.unistd.read
@@ -354,6 +356,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10

diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
@@ -17,6 +17,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
+    # dlfcn.h entrypoints
+    libc.src.dlfcn.dlclose
+    libc.src.dlfcn.dlerror
+    libc.src.dlfcn.dlopen
+    libc.src.dlfcn.dlsym
+
     # errno.h entrypoints
     libc.src.errno.errno
 
@@ -302,6 +308,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.dup3
     libc.src.unistd.execve
     libc.src.unistd.fchdir
+    libc.src.unistd.fpathconf
     libc.src.unistd.fsync
     libc.src.unistd.ftruncate
     libc.src.unistd.getcwd
@@ -313,6 +320,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.unistd.link
     libc.src.unistd.linkat
     libc.src.unistd.lseek
+    libc.src.unistd.pathconf
     libc.src.unistd.pipe
     libc.src.unistd.pread
     libc.src.unistd.pwrite
@@ -371,6 +379,7 @@ set(TARGET_LIBM_ENTRYPOINTS
     libc.src.math.cos
     libc.src.math.cosf
     libc.src.math.coshf
+    libc.src.math.cospif
     libc.src.math.erff
     libc.src.math.exp
     libc.src.math.exp10

diff --git a/libc/config/linux/x86_64/headers.txt b/libc/config/linux/x86_64/headers.txt
@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.dirent
+    libc.include.dlfcn
     libc.include.errno
     libc.include.fcntl
     libc.include.features

diff --git a/libc/docs/dev/undefined_behavior.rst b/libc/docs/dev/undefined_behavior.rst
@@ -89,3 +89,7 @@ The C23 standard states that if the value of the ``rnd`` argument of the
 the value of a math rounding direction macro, the direction of rounding is
 unspecified. LLVM's libc chooses to use the ``FP_INT_TONEAREST`` rounding
 direction in this case.
+
+Non-const Constant Return Values
+--------------------------------
+Some libc functions, like ``dlerror()``, return ``char *`` instead of ``const char *`` and then tell the caller they promise not to to modify this value. Any modification of this value is undefined behavior.
diff --git a/libc/docs/math/index.rst b/libc/docs/math/index.rst
@@ -128,7 +128,7 @@ Basic Operations
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | f16div           | |check|\*        | |check|\*       | |check|\*              | N/A                  | |check|                | 7.12.14.4              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| f16fma           | |check|          | |check|         | |check|                | N/A                  | |check|                | 7.12.14.5              | F.10.11                    |
+| f16fma           | |check|\*        | |check|\*       | |check|\*              | N/A                  | |check|                | 7.12.14.5              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | f16sub           | |check|\*        | |check|\*       | |check|\*              | N/A                  | |check|                | 7.12.14.2              | F.10.11                    |
 +------------------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
@@ -274,7 +274,7 @@ Higher Math Functions
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | cosh      | |check|          |                 |                        |                      |                        | 7.12.5.4               | F.10.2.4                   |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
-| cospi     |                  |                 |                        |                      |                        | 7.12.4.12              | F.10.1.12                  |
+| cospi     | |check|          |                 |                        |                      |                        | 7.12.4.12              | F.10.1.12                  |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+
 | dsqrt     | N/A              | N/A             |                        | N/A                  |                        | 7.12.14.6              | F.10.11                    |
 +-----------+------------------+-----------------+------------------------+----------------------+------------------------+------------------------+----------------------------+

diff --git a/libc/hdr/CMakeLists.txt b/libc/hdr/CMakeLists.txt
@@ -78,6 +78,24 @@ add_proxy_header_library(
     libc.include.llvm-libc-macros.sys_epoll_macros
 )
 
+add_proxy_header_library(
+  sys_stat_macros
+  HDRS
+    sys_stat_macros.h
+  FULL_BUILD_DEPENDS
+    libc.include.sys_stat
+    libc.include.llvm-libc-macros.sys_stat_macros
+)
+
+add_proxy_header_library(
+  unistd_macros
+  HDRS
+    unistd_macros.h
+  FULL_BUILD_DEPENDS
+    libc.include.unistd
+    libc.include.llvm-libc-macros.unistd_macros
+)
+
 add_proxy_header_library(
   time_macros
   HDRS
@@ -97,4 +115,13 @@ add_proxy_header_library(
     libc.include.float
 )
 
+add_proxy_header_library(
+  limits_macros
+  HDRS
+    limits_macros.h
+  FULL_BUILD_DEPENDS
+    libc.include.limits
+    libc.include.llvm-libc-macros.limits_macros
+)
+
 add_subdirectory(types)
diff --git a/libc/hdr/limits_macros.h b/libc/hdr/limits_macros.h
@@ -0,0 +1,22 @@
+//===-- Definition of macros from limits.h --------------------------------===//
+//
+// 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_LIBC_HDR_LIMITS_MACROS_H
+#define LLVM_LIBC_HDR_LIMITS_MACROS_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-macros/limits-macros.h"
+
+#else // Overlay mode
+
+#include <limits.h>
+
+#endif // LLVM_LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_LIMITS_MACROS_H
diff --git a/libc/hdr/math_macros.h b/libc/hdr/math_macros.h
@@ -15,6 +15,11 @@
 
 #else // Overlay mode
 
+// GCC will include CXX headers when __cplusplus is defined. This behavior
+// can be suppressed by defining _GLIBCXX_INCLUDE_NEXT_C_HEADERS.
+#if defined(__GNUC__) && !defined(__clang__)
+#define _GLIBCXX_INCLUDE_NEXT_C_HEADERS
+#endif
 #include <math.h>
 
 // Some older math.h header does not have FP_INT_* constants yet.

diff --git a/libc/hdr/sys_stat_macros.h b/libc/hdr/sys_stat_macros.h
@@ -0,0 +1,22 @@
+//===-- Definition of macros from sys/stat.h ------------------------------===//
+//
+// 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_LIBC_HDR_SYS_STAT_MACROS_H
+#define LLVM_LIBC_HDR_SYS_STAT_MACROS_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-macros/sys-stat-macros.h"
+
+#else // Overlay mode
+
+#include <sys/stat.h>
+
+#endif // LLVM_LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_SYS_STAT_MACROS_H
diff --git a/libc/hdr/unistd_macros.h b/libc/hdr/unistd_macros.h
@@ -0,0 +1,22 @@
+//===-- Definition of macros from unistd.h --------------------------------===//
+//
+// 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_LIBC_HDR_UNISTD_MACROS_H
+#define LLVM_LIBC_HDR_UNISTD_MACROS_H
+
+#ifdef LIBC_FULL_BUILD
+
+#include "include/llvm-libc-macros/unistd-macros.h"
+
+#else // Overlay mode
+
+#include <unistd.h>
+
+#endif // LLVM_LIBC_FULL_BUILD
+
+#endif // LLVM_LIBC_HDR_UNISTD_MACROS_H
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
@@ -51,6 +51,15 @@ add_gen_header(
     .llvm_libc_common_h
 )
 
+add_gen_header(
+  dlfcn
+  DEF_FILE dlfcn.h.def
+  GEN_HDR dlfcn.h
+  DEPENDS
+    .llvm-libc-macros.dlfcn_macros
+    .llvm_libc_common_h
+)
+
 add_gen_header(
   features
   DEF_FILE features.h.def

diff --git a/libc/include/dlfcn.h.def b/libc/include/dlfcn.h.def
@@ -0,0 +1,17 @@
+//===-- C standard library header dlfcn.h ---------------------------------===//
+//
+// 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_LIBC_DLFCN_H
+#define LLVM_LIBC_DLFCN_H
+
+#include "__llvm-libc-common.h"
+#include "llvm-libc-macros/dlfcn-macros.h"
+
+%%public_api()
+
+#endif // LLVM_LIBC_DLFCN_H
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -277,3 +277,9 @@ add_macro_header(
   HDR
     stdckdint-macros.h
 )
+
+add_macro_header(
+  dlfcn_macros
+  HDR
+    dlfcn-macros.h
+)
diff --git a/libc/include/llvm-libc-macros/dlfcn-macros.h b/libc/include/llvm-libc-macros/dlfcn-macros.h
@@ -0,0 +1,23 @@
+//===-- Definition of macros from dlfcn.h ---------------------------------===//
+//
+// 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_LIBC_MACROS_DLFCN_MACROS_H
+#define LLVM_LIBC_MACROS_DLFCN_MACROS_H
+
+#define RTLD_LAZY 0x00001
+#define RTLD_NOW 0x00002
+#define RTLD_GLOBAL 0x00100
+#define RTLD_LOCAL 0
+
+// Non-standard stuff here
+#define RTLD_BINDING_MASK 0x3
+#define RTLD_NOLOAD 0x00004
+#define RTLD_DEEPBIND 0x00008
+#define RTLD_NODELETE 0x01000
+
+#endif // LLVM_LIBC_MACROS_DLFCN_MACROS_H
diff --git a/libc/include/llvm-libc-macros/limits-macros.h b/libc/include/llvm-libc-macros/limits-macros.h
@@ -225,4 +225,16 @@
 #define ULLONG_MIN 0ULL
 #endif // ULLONG_MIN
 
+#ifndef _POSIX_MAX_CANON
+#define _POSIX_MAX_CANON 255
+#endif
+
+#ifndef _POSIX_MAX_INPUT
+#define _POSIX_MAX_INPUT 255
+#endif
+
+#ifndef _POSIX_NAME_MAX
+#define _POSIX_PATH_MAX 256
+#endif
+
 #endif // LLVM_LIBC_MACROS_LIMITS_MACROS_H
diff --git a/libc/include/llvm-libc-macros/linux/unistd-macros.h b/libc/include/llvm-libc-macros/linux/unistd-macros.h
@@ -18,6 +18,33 @@
 #define _SC_PAGESIZE 1
 #define _SC_PAGE_SIZE _SC_PAGESIZE
 
+#define _PC_FILESIZEBITS 0
+#define _PC_LINK_MAX 1
+#define _PC_MAX_CANON 2
+#define _PC_MAX_INPUT 3
+#define _PC_NAME_MAX 4
+#define _PC_PATH_MAX 5
+#define _PC_PIPE_BUF 6
+#define _PC_2_SYMLINKS 7
+#define _PC_ALLOC_SIZE_MIN 8
+#define _PC_REC_INCR_XFER_SIZE 9
+#define _PC_REC_MAX_XFER_SIZE 10
+#define _PC_REC_MIN_XFER_SIZE 11
+#define _PC_REC_XFER_ALIGN 12
+#define _PC_SYMLINK_MAX 13
+#define _PC_CHOWN_RESTRICTED 14
+#define _PC_NO_TRUNC 15
+#define _PC_VDISABLE 16
+#define _PC_ASYNC_IO 17
+#define _PC_PRIO_IO 18
+#define _PC_SYNC_IO 19
+
+// TODO: Move these limit macros to a separate file
+#define _POSIX_CHOWN_RESTRICTED 1
+#define _POSIX_PIPE_BUF 512
+#define _POSIX_NO_TRUNC 1
+#define _POSIX_VDISABLE '\0'
+
 // Macro to set up the call to the __llvm_libc_syscall function
 // This is to prevent the call from having fewer than 6 arguments, since six
 // arguments are always passed to the syscall. Unnecessary arguments are

diff --git a/libc/spec/linux.td b/libc/spec/linux.td
@@ -112,7 +112,19 @@ def Linux : StandardSpec<"Linux"> {
       [], // Macros
       [], // Types
       [], // Enumerations
-      []  // Functions
+      [
+        FunctionSpec<
+          "prctl",
+          RetValSpec<IntType>,
+          [
+            ArgSpec<IntType>,
+            ArgSpec<UnsignedLongType>,
+            ArgSpec<UnsignedLongType>,
+            ArgSpec<UnsignedLongType>,
+            ArgSpec<UnsignedLongType>,
+          ]
+        >,
+      ]  // Functions
   >;
 
   HeaderSpec SysRandom = HeaderSpec<

diff --git a/libc/spec/llvm_libc_ext.td b/libc/spec/llvm_libc_ext.td
@@ -69,6 +69,10 @@ def LLVMLibcExt : StandardSpec<"llvm_libc_ext"> {
           GuardedFunctionSpec<"f16divf", RetValSpec<Float16Type>, [ArgSpec<FloatType>, ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16divl", RetValSpec<Float16Type>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
 
+          GuardedFunctionSpec<"f16fma", RetValSpec<Float16Type>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>, ArgSpec<DoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
+          GuardedFunctionSpec<"f16fmaf", RetValSpec<Float16Type>, [ArgSpec<FloatType>, ArgSpec<FloatType>, ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,
+          GuardedFunctionSpec<"f16fmal", RetValSpec<Float16Type>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
+
           GuardedFunctionSpec<"f16sqrt", RetValSpec<Float16Type>, [ArgSpec<DoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16sqrtf", RetValSpec<Float16Type>, [ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16sqrtl", RetValSpec<Float16Type>, [ArgSpec<LongDoubleType>], "LIBC_TYPES_HAS_FLOAT16">,

diff --git a/libc/spec/posix.td b/libc/spec/posix.td
@@ -222,6 +222,40 @@ def POSIX : StandardSpec<"POSIX"> {
       []  // Functions
   >;
 
+  HeaderSpec DlFcn = HeaderSpec<
+    "dlfcn.h",
+    [
+      Macro<"RTLD_LAZY">,
+      Macro<"RTLD_NOW">,
+      Macro<"RTLD_GLOBAL">,
+      Macro<"RTLD_LOCAL">,
+    ],
+    [],  // Types
+    [], // Enumerations
+    [
+      FunctionSpec<
+          "dlclose",
+          RetValSpec<IntType>,
+          [ArgSpec<VoidPtr>]
+      >,
+      FunctionSpec<
+          "dlerror",
+          RetValSpec<CharPtr>,
+          []
+      >,
+      FunctionSpec<
+          "dlopen",
+          RetValSpec<VoidPtr>,
+          [ArgSpec<ConstCharPtr>, ArgSpec<IntType>]
+      >,
+      FunctionSpec<
+          "dlsym",
+          RetValSpec<VoidPtr>,
+          [ArgSpec<VoidRestrictedPtr>, ArgSpec<ConstCharRestrictedPtr>]
+      >,
+    ]
+  >;
+
   HeaderSpec FCntl = HeaderSpec<
     "fcntl.h",
     [], // Macros
@@ -1690,6 +1724,7 @@ def POSIX : StandardSpec<"POSIX"> {
     ArpaInet,
     CType,
     Dirent,
+    DlFcn,
     Errno,
     FCntl,
     PThread,

diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
@@ -477,9 +477,6 @@ def StdC : StandardSpec<"stdc"> {
           FunctionSpec<"fma", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,
           FunctionSpec<"fmaf", RetValSpec<FloatType>, [ArgSpec<FloatType>, ArgSpec<FloatType>, ArgSpec<FloatType>]>,
 
-          GuardedFunctionSpec<"f16fma", RetValSpec<Float16Type>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>, ArgSpec<DoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
-          GuardedFunctionSpec<"f16fmaf", RetValSpec<Float16Type>, [ArgSpec<FloatType>, ArgSpec<FloatType>, ArgSpec<FloatType>], "LIBC_TYPES_HAS_FLOAT16">,
-          GuardedFunctionSpec<"f16fmal", RetValSpec<Float16Type>, [ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>, ArgSpec<LongDoubleType>], "LIBC_TYPES_HAS_FLOAT16">,
           GuardedFunctionSpec<"f16fmaf128", RetValSpec<Float16Type>, [ArgSpec<Float128Type>, ArgSpec<Float128Type>, ArgSpec<Float128Type>], "LIBC_TYPES_HAS_FLOAT16_AND_FLOAT128">,
 
           FunctionSpec<"fmod", RetValSpec<DoubleType>, [ArgSpec<DoubleType>, ArgSpec<DoubleType>]>,

diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
@@ -1,6 +1,7 @@
 add_subdirectory(__support)
 
 add_subdirectory(ctype)
+add_subdirectory(dlfcn)
 add_subdirectory(errno)
 add_subdirectory(fenv)
 add_subdirectory(inttypes)

diff --git a/libc/src/__support/File/linux/CMakeLists.txt b/libc/src/__support/File/linux/CMakeLists.txt
@@ -1,3 +1,4 @@
+# TODO: migrate to proxy headers
 add_object_library(
   file
   SRCS
@@ -8,6 +9,7 @@ add_object_library(
     libc.include.fcntl
     libc.include.stdio
     libc.include.sys_syscall
+    libc.include.sys_stat
     libc.src.__support.CPP.new
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno

diff --git a/libc/src/__support/threads/sleep.h b/libc/src/__support/threads/sleep.h
@@ -22,8 +22,10 @@ LIBC_INLINE void sleep_briefly() {
   __builtin_amdgcn_s_sleep(2);
 #elif defined(LIBC_TARGET_ARCH_IS_X86)
   __builtin_ia32_pause();
-#elif defined(LIBC_TARGET_ARCH_IS_AARCH64)
+#elif defined(LIBC_TARGET_ARCH_IS_AARCH64) && __has_builtin(__builtin_arm_isb)
   __builtin_arm_isb(0xf);
+#elif defined(LIBC_TARGET_ARCH_IS_AARCH64)
+  asm volatile("isb\n" ::: "memory");
 #else
   // Simply do nothing if sleeping isn't supported on this platform.
 #endif

diff --git a/libc/src/dlfcn/CMakeLists.txt b/libc/src/dlfcn/CMakeLists.txt
@@ -0,0 +1,40 @@
+add_entrypoint_object(
+  dlclose
+  SRCS
+    dlclose.cpp
+  HDRS
+    dlclose.h
+)
+
+add_entrypoint_object(
+  dlerror
+  SRCS
+    dlerror.cpp
+  HDRS
+    dlerror.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dlopen
+  SRCS
+    dlopen.cpp
+  HDRS
+    dlopen.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dlsym
+  SRCS
+    dlsym.cpp
+  HDRS
+    dlsym.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
diff --git a/libc/src/dlfcn/dlclose.cpp b/libc/src/dlfcn/dlclose.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of dlclose -----------------------------------------===//
+//
+// 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 "dlclose.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+// TODO(@izaakschroeder): https://github.com/llvm/llvm-project/issues/97917
+LLVM_LIBC_FUNCTION(int, dlclose, (void *)) { return -1; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlclose.h b/libc/src/dlfcn/dlclose.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlclose ------------------------*- 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_LIBC_SRC_DLFCN_DLCLOSE_H
+#define LLVM_LIBC_SRC_DLFCN_DLCLOSE_H
+
+namespace LIBC_NAMESPACE {
+
+int dlclose(void *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLCLOSE_H
diff --git a/libc/src/dlfcn/dlerror.cpp b/libc/src/dlfcn/dlerror.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of delerror ----------------------------------------===//
+//
+// 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 "dlerror.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+// TODO(@izaakschroeder): https://github.com/llvm/llvm-project/issues/97918
+LLVM_LIBC_FUNCTION(char *, dlerror, ()) {
+  return const_cast<char *>("unsupported");
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlerror.h b/libc/src/dlfcn/dlerror.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlerror ------------------------*- 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_LIBC_SRC_DLFCN_DLERROR_H
+#define LLVM_LIBC_SRC_DLFCN_DLERROR_H
+
+namespace LIBC_NAMESPACE {
+
+char *dlerror();
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLERROR_H
diff --git a/libc/src/dlfcn/dlopen.cpp b/libc/src/dlfcn/dlopen.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of dlopen -----------------------------------------===//
+//
+// 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 "dlopen.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+// TODO(@izaakschroeder): https://github.com/llvm/llvm-project/issues/97919
+LLVM_LIBC_FUNCTION(void *, dlopen, (const char *, int)) { return nullptr; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlopen.h b/libc/src/dlfcn/dlopen.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlopen -------------------------*- 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_LIBC_SRC_DLFCN_DLOPEN_H
+#define LLVM_LIBC_SRC_DLFCN_DLOPEN_H
+
+namespace LIBC_NAMESPACE {
+
+void *dlopen(const char *, int);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLOPEN_H
diff --git a/libc/src/dlfcn/dlsym.cpp b/libc/src/dlfcn/dlsym.cpp
@@ -0,0 +1,18 @@
+//===-- Implementation of dlsym ------------------------------------------===//
+//
+// 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 "dlsym.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+// TODO(@izaakschroeder): https://github.com/llvm/llvm-project/issues/97920
+LLVM_LIBC_FUNCTION(void *, dlsym, (void *, const char *)) { return nullptr; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlsym.h b/libc/src/dlfcn/dlsym.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlsym --------------------------*- 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_LIBC_SRC_DLFCN_DLSYM_H
+#define LLVM_LIBC_SRC_DLFCN_DLSYM_H
+
+namespace LIBC_NAMESPACE {
+
+void *dlsym(void *, const char *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLSYM_H
diff --git a/libc/src/math/CMakeLists.txt b/libc/src/math/CMakeLists.txt
@@ -81,6 +81,7 @@ add_math_entrypoint_object(cos)
 add_math_entrypoint_object(cosf)
 add_math_entrypoint_object(cosh)
 add_math_entrypoint_object(coshf)
+add_math_entrypoint_object(cospif)
 
 add_math_entrypoint_object(erf)
 add_math_entrypoint_object(erff)

diff --git a/libc/src/math/cospif.h b/libc/src/math/cospif.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for cospif ------------------------*- 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_LIBC_SRC_MATH_COSPIF_H
+#define LLVM_LIBC_SRC_MATH_COSPIF_H
+
+namespace LIBC_NAMESPACE {
+
+float cospif(float x);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_MATH_COSPIF_H
diff --git a/libc/src/math/generic/CMakeLists.txt b/libc/src/math/generic/CMakeLists.txt
@@ -217,6 +217,23 @@ add_entrypoint_object(
     -O3
 )
 
+add_entrypoint_object(
+  cospif
+  SRCS
+    cospif.cpp
+  HDRS
+    ../cospif.h
+  DEPENDS
+    .sincosf_utils
+    libc.src.__support.FPUtil.fenv_impl
+    libc.src.__support.FPUtil.fp_bits
+    libc.src.__support.FPUtil.fma
+    libc.src.__support.FPUtil.multiply_add
+    libc.src.__support.macros.optimization
+  COMPILE_OPTIONS
+    -O3
+)
+
 add_entrypoint_object(
   sin
   SRCS

diff --git a/libc/src/math/generic/cos.cpp b/libc/src/math/generic/cos.cpp
@@ -61,7 +61,7 @@ LLVM_LIBC_FUNCTION(double, cos, (double x)) {
 
   DoubleDouble y;
   unsigned k;
-  generic::LargeRangeReduction<NO_FMA> range_reduction_large;
+  generic::LargeRangeReduction<NO_FMA> range_reduction_large{};
 
   // |x| < 2^32 (with FMA) or |x| < 2^23 (w/o FMA)
   if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT)) {

diff --git a/libc/src/math/generic/cospif.cpp b/libc/src/math/generic/cospif.cpp
@@ -0,0 +1,96 @@
+//===-- Single-precision cospi function -----------------------------------===//
+//
+// 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 "src/math/cospif.h"
+#include "sincosf_utils.h"
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/optimization.h"            // LIBC_UNLIKELY
+#include "src/__support/macros/properties/cpu_features.h" // LIBC_TARGET_CPU_HAS_FMA
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(float, cospif, (float x)) {
+  using FPBits = typename fputil::FPBits<float>;
+
+  FPBits xbits(x);
+  Sign xsign = xbits.sign();
+  xbits.set_sign(Sign::POS);
+
+  uint32_t x_abs = xbits.uintval();
+  double xd = static_cast<double>(xbits.get_val());
+
+  // Range reduction:
+  // For |x| > 1/32, we perform range reduction as follows:
+  // Find k and y such that:
+  //   x = (k + y) * 1/32
+  //   k is an integer
+  //   |y| < 0.5
+  //
+  // This is done by performing:
+  //   k = round(x * 32)
+  //   y = x * 32 - k
+  //
+  // Once k and y are computed, we then deduce the answer by the cosine of sum
+  // formula:
+  //   cospi(x) = cos((k + y)*pi/32)
+  //          = cos(y*pi/32) * cos(k*pi/32) - sin(y*pi/32) * sin(k*pi/32)
+  // The values of sin(k*pi/32) and cos(k*pi/32) for k = 0..63 are precomputed
+  // and stored using a vector of 32 doubles. Sin(y*pi/32) and cos(y*pi/32) are
+  // computed using degree-7 and degree-6 minimax polynomials generated by
+  // Sollya respectively.
+
+  // The exhautive test passes for smaller values
+  if (LIBC_UNLIKELY(x_abs < 0x38A2'F984U)) {
+
+#if defined(LIBC_TARGET_CPU_HAS_FMA)
+    return fputil::multiply_add(xbits.get_val(), -0x1.0p-25f, 1.0f);
+#else
+    return static_cast<float>(fputil::multiply_add(xd, -0x1.0p-25, 1.0));
+#endif // LIBC_TARGET_CPU_HAS_FMA
+  }
+
+  // Numbers greater or equal to 2^23 are always integers or NaN
+  if (LIBC_UNLIKELY(x_abs >= 0x4B00'0000)) {
+
+    if (LIBC_UNLIKELY(x_abs < 0x4B80'0000)) {
+      return (x_abs & 0x1) ? -1.0f : 1.0f;
+    }
+
+    // x is inf or nan.
+    if (LIBC_UNLIKELY(x_abs >= 0x7f80'0000U)) {
+      if (x_abs == 0x7f80'0000U) {
+        fputil::set_errno_if_required(EDOM);
+        fputil::raise_except_if_required(FE_INVALID);
+      }
+      return x + FPBits::quiet_nan().get_val();
+    }
+
+    return 1.0f;
+  }
+
+  // Combine the results with the sine of sum formula:
+  //   cos(pi * x) = cos((k + y)*pi/32)
+  //          = cos(y*pi/32) * cos(k*pi/32) - sin(y*pi/32) * sin(k*pi/32)
+  //          = (cosm1_y + 1) * cos_k - sin_y * sin_k
+  //          = (cosm1_y * cos_k + cos_k) - sin_y * sin_k
+  double sin_k, cos_k, sin_y, cosm1_y;
+
+  sincospif_eval(xd, sin_k, cos_k, sin_y, cosm1_y);
+
+  if (LIBC_UNLIKELY(sin_y == 0 && cos_k == 0)) {
+    return FPBits::zero(xsign).get_val();
+  }
+
+  return static_cast<float>(fputil::multiply_add(
+      sin_y, -sin_k, fputil::multiply_add(cosm1_y, cos_k, cos_k)));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/math/generic/erff.cpp b/libc/src/math/generic/erff.cpp
@@ -127,15 +127,6 @@ LLVM_LIBC_FUNCTION(float, erff, (float x)) {
   uint32_t x_u = xbits.uintval();
   uint32_t x_abs = x_u & 0x7fff'ffffU;
 
-  // Exceptional values
-  if (LIBC_UNLIKELY(x_abs == 0x3f65'9229U)) // |x| = 0x1.cb2452p-1f
-    return x < 0.0f ? fputil::round_result_slightly_down(-0x1.972ea8p-1f)
-                    : fputil::round_result_slightly_up(0x1.972ea8p-1f);
-  if (LIBC_UNLIKELY(x_abs == 0x4004'1e6aU)) // |x| = 0x1.083cd4p+1f
-    return x < 0.0f ? fputil::round_result_slightly_down(-0x1.fe3462p-1f)
-                    : fputil::round_result_slightly_up(0x1.fe3462p-1f);
-
-  // if (LIBC_UNLIKELY(x_abs > 0x407a'd444U)) {
   if (LIBC_UNLIKELY(x_abs >= 0x4080'0000U)) {
     const float ONE[2] = {1.0f, -1.0f};
     const float SMALL[2] = {-0x1.0p-25f, 0x1.0p-25f};
@@ -149,6 +140,21 @@ LLVM_LIBC_FUNCTION(float, erff, (float x)) {
     return ONE[sign] + SMALL[sign];
   }
 
+  // Exceptional mask = common 0 bits of 2 exceptional values.
+  constexpr uint32_t EXCEPT_MASK = 0x809a'6184U;
+
+  if (LIBC_UNLIKELY((x_abs & EXCEPT_MASK) == 0)) {
+    // Exceptional values
+    if (LIBC_UNLIKELY(x_abs == 0x3f65'9229U)) // |x| = 0x1.cb2452p-1f
+      return x < 0.0f ? fputil::round_result_slightly_down(-0x1.972ea8p-1f)
+                      : fputil::round_result_slightly_up(0x1.972ea8p-1f);
+    if (LIBC_UNLIKELY(x_abs == 0x4004'1e6aU)) // |x| = 0x1.083cd4p+1f
+      return x < 0.0f ? fputil::round_result_slightly_down(-0x1.fe3462p-1f)
+                      : fputil::round_result_slightly_up(0x1.fe3462p-1f);
+    if (x_abs == 0U)
+      return x;
+  }
+
   // Polynomial approximation:
   //   erf(x) ~ x * (c0 + c1 * x^2 + c2 * x^4 + ... + c7 * x^14)
   double xd = static_cast<double>(x);

diff --git a/libc/src/math/generic/sin.cpp b/libc/src/math/generic/sin.cpp
@@ -62,7 +62,7 @@ LLVM_LIBC_FUNCTION(double, sin, (double x)) {
 
   DoubleDouble y;
   unsigned k;
-  generic::LargeRangeReduction<NO_FMA> range_reduction_large;
+  generic::LargeRangeReduction<NO_FMA> range_reduction_large{};
 
   // |x| < 2^32 (with FMA) or |x| < 2^23 (w/o FMA)
   if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT)) {

diff --git a/libc/src/math/generic/sincos.cpp b/libc/src/math/generic/sincos.cpp
@@ -63,7 +63,7 @@ LLVM_LIBC_FUNCTION(void, sincos, (double x, double *sin_x, double *cos_x)) {
 
   DoubleDouble y;
   unsigned k;
-  generic::LargeRangeReduction<NO_FMA> range_reduction_large;
+  generic::LargeRangeReduction<NO_FMA> range_reduction_large{};
 
   // |x| < 2^32 (with FMA) or |x| < 2^23 (w/o FMA)
   if (LIBC_LIKELY(x_e < FPBits::EXP_BIAS + FAST_PASS_EXPONENT)) {

diff --git a/libc/src/math/generic/sinpif.cpp b/libc/src/math/generic/sinpif.cpp
@@ -26,13 +26,13 @@ LLVM_LIBC_FUNCTION(float, sinpif, (float x)) {
   double xd = static_cast<double>(x);
 
   // Range reduction:
-  // For |x| > pi/32, we perform range reduction as follows:
+  // For |x| > 1/32, we perform range reduction as follows:
   // Find k and y such that:
   //   x = (k + y) * 1/32
   //   k is an integer
   //   |y| < 0.5
-  // For small range (|x| < 2^45 when FMA instructions are available, 2^22
-  // otherwise), this is done by performing:
+  //
+  // This is done by performing:
   //   k = round(x * 32)
   //   y = x * 32 - k
   //

diff --git a/libc/src/search/hsearch.cpp b/libc/src/search/hsearch.cpp
@@ -14,7 +14,7 @@
 
 namespace LIBC_NAMESPACE {
 LLVM_LIBC_FUNCTION(ENTRY *, hsearch, (ENTRY item, ACTION action)) {
-  ENTRY *result;
+  ENTRY *result = nullptr;
   if (internal::global_hash_table == nullptr) {
     // If global_hash_table is null, we create a new hash table with a minimal
     // capacity. Such hashtable will be expanded as needed.

diff --git a/libc/src/sys/statvfs/linux/CMakeLists.txt b/libc/src/sys/statvfs/linux/CMakeLists.txt
@@ -8,6 +8,7 @@ add_header_library(
     libc.src.__support.common
     libc.src.__support.CPP.optional
     libc.include.sys_syscall
+    libc.include.llvm-libc-types.struct_statvfs
 )
 
 add_entrypoint_object(

diff --git a/libc/src/unistd/CMakeLists.txt b/libc/src/unistd/CMakeLists.txt
@@ -69,6 +69,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.fork
 )
 
+add_entrypoint_object(
+  fpathconf
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.fpathconf
+)
+
 add_entrypoint_object(
   execv
   ALIAS
@@ -160,6 +167,14 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.lseek
 )
 
+add_entrypoint_object(
+  pathconf
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.pathconf
+)
+
+
 add_entrypoint_object(
   pipe
   ALIAS

diff --git a/libc/src/unistd/fpathconf.h b/libc/src/unistd/fpathconf.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for fpathconf ---------------------*- 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_LIBC_SRC_UNISTD_FPATHCONF_H
+#define LLVM_LIBC_SRC_UNISTD_FPATHCONF_H
+
+namespace LIBC_NAMESPACE {
+
+long fpathconf(int fd, int name);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_UNISTD_FSYNC_H
diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
@@ -105,6 +105,20 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  fpathconf
+  SRCS
+    fpathconf.cpp
+  HDRS
+    ../fpathconf.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+    libc.src.unistd.linux.pathconf_utils
+)
+
 add_entrypoint_object(
   execv
   SRCS
@@ -273,6 +287,34 @@ add_entrypoint_object(
     libc.src.errno.errno
 )
 
+add_entrypoint_object(
+  pathconf
+  SRCS
+    pathconf.cpp
+  HDRS
+    ../pathconf.h
+  DEPENDS
+    libc.include.unistd
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+    libc.src.unistd.linux.pathconf_utils
+)
+
+add_object_library(
+  pathconf_utils
+  SRCS
+    pathconf_utils.cpp
+  HDRS
+    pathconf_utils.h
+  DEPENDS
+    libc.hdr.limits_macros
+    libc.hdr.unistd_macros
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+    libc.src.sys.statvfs.linux.statfs_utils
+)
+
 add_entrypoint_object(
   pipe
   SRCS

diff --git a/libc/src/unistd/linux/fpathconf.cpp b/libc/src/unistd/linux/fpathconf.cpp
@@ -0,0 +1,24 @@
+//===-- Linux implementation of fpathconf ---------------------------------===//
+//
+// 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 "src/unistd/fpathconf.h"
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/sys/statvfs/linux/statfs_utils.h"
+#include "src/unistd/linux/pathconf_utils.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(long, fpathconf, (int fd, int name)) {
+  if (cpp::optional<statfs_utils::LinuxStatFs> result =
+          statfs_utils::linux_fstatfs(fd))
+    return pathconfig(result.value(), name);
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/unistd/linux/pathconf.cpp b/libc/src/unistd/linux/pathconf.cpp
@@ -0,0 +1,23 @@
+//===-- Linux implementation of pathconf ----------------------------------===//
+//
+// 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 "src/unistd/pathconf.h"
+#include "src/errno/libc_errno.h"
+#include "src/sys/statvfs/linux/statfs_utils.h"
+#include "src/unistd/linux/pathconf_utils.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(long, pathconf, (const char *path, int name)) {
+  if (cpp::optional<statfs_utils::LinuxStatFs> result =
+          statfs_utils::linux_statfs(path))
+    return pathconfig(result.value(), name);
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE