Index: llvm/include/llvm/Analysis/TargetLibraryInfo.def
===================================================================
--- llvm/include/llvm/Analysis/TargetLibraryInfo.def
+++ llvm/include/llvm/Analysis/TargetLibraryInfo.def
@@ -366,6 +366,9 @@
 /// void *__memmove_chk(void *s1, const void *s2, size_t n, size_t s1size);
 TLI_DEFINE_ENUM_INTERNAL(memmove_chk)
 TLI_DEFINE_STRING_INTERNAL("__memmove_chk")
+/// void *__mempcpy_chk(void *s1, const void *s2, size_t n, size_t s1size);
+TLI_DEFINE_ENUM_INTERNAL(mempcpy_chk)
+TLI_DEFINE_STRING_INTERNAL("__mempcpy_chk")
 /// void *__memset_chk(void *s, char v, size_t n, size_t s1size);
 TLI_DEFINE_ENUM_INTERNAL(memset_chk)
 TLI_DEFINE_STRING_INTERNAL("__memset_chk")
Index: llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
+++ llvm/include/llvm/Transforms/Utils/BuildLibCalls.h
@@ -96,6 +96,10 @@
                        IRBuilderBase &B, const DataLayout &DL,
                        const TargetLibraryInfo *TLI);
 
+  /// Emit a call to the mempcpy function.
+  Value *emitMemPCpy(Value *Dst, Value *Src, Value *Len, IRBuilderBase &B,
+                     const DataLayout &DL, const TargetLibraryInfo *TLI);
+
   /// Emit a call to the memchr function. This assumes that Ptr is a pointer,
   /// Val is an i32 value, and Len is an 'intptr_t' value.
   Value *emitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilderBase &B,
Index: llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
+++ llvm/include/llvm/Transforms/Utils/SimplifyLibCalls.h
@@ -59,6 +59,7 @@
   Value *optimizeStrpCpyChk(CallInst *CI, IRBuilderBase &B, LibFunc Func);
   Value *optimizeStrpNCpyChk(CallInst *CI, IRBuilderBase &B, LibFunc Func);
   Value *optimizeStrLenChk(CallInst *CI, IRBuilderBase &B);
+  Value *optimizeMemPCpyChk(CallInst *CI, IRBuilderBase &B);
   Value *optimizeMemCCpyChk(CallInst *CI, IRBuilderBase &B);
   Value *optimizeSNPrintfChk(CallInst *CI, IRBuilderBase &B);
   Value *optimizeSPrintfChk(CallInst *CI,IRBuilderBase &B);
Index: llvm/lib/Analysis/TargetLibraryInfo.cpp
===================================================================
--- llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -847,6 +847,7 @@
     return (NumParams >= 2 && FTy.getParamType(1)->isPointerTy());
 
   case LibFunc_memcpy_chk:
+  case LibFunc_mempcpy_chk:
   case LibFunc_memmove_chk:
     --NumParams;
     if (!IsSizeTTy(FTy.getParamType(NumParams)))
Index: llvm/lib/Transforms/Utils/BuildLibCalls.cpp
===================================================================
--- llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -1026,6 +1026,15 @@
   return CI;
 }
 
+Value *llvm::emitMemPCpy(Value *Dst, Value *Src, Value *Len, IRBuilderBase &B,
+                         const DataLayout &DL, const TargetLibraryInfo *TLI) {
+  LLVMContext &Context = B.GetInsertBlock()->getContext();
+  return emitLibCall(
+      LibFunc_mempcpy, B.getInt8PtrTy(),
+      {B.getInt8PtrTy(), B.getInt8PtrTy(), DL.getIntPtrType(Context)},
+      {Dst, Src, Len}, B, TLI);
+}
+
 Value *llvm::emitMemChr(Value *Ptr, Value *Val, Value *Len, IRBuilderBase &B,
                         const DataLayout &DL, const TargetLibraryInfo *TLI) {
   LLVMContext &Context = B.GetInsertBlock()->getContext();
Index: llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -3281,6 +3281,19 @@
   return nullptr;
 }
 
+Value *FortifiedLibCallSimplifier::optimizeMemPCpyChk(CallInst *CI,
+                                                      IRBuilderBase &B) {
+  const DataLayout &DL = CI->getModule()->getDataLayout();
+  if (isFortifiedCallFoldable(CI, 3, 2)) {
+    CallInst *NewCI =
+        cast<CallInst>(emitMemPCpy(CI->getArgOperand(0), CI->getArgOperand(1),
+                                   CI->getArgOperand(2), B, DL, TLI));
+    NewCI->setAttributes(CI->getAttributes());
+    return NewCI;
+  }
+  return nullptr;
+}
+
 Value *FortifiedLibCallSimplifier::optimizeStrpCpyChk(CallInst *CI,
                                                       IRBuilderBase &B,
                                                       LibFunc Func) {
@@ -3470,6 +3483,8 @@
   switch (Func) {
   case LibFunc_memcpy_chk:
     return optimizeMemCpyChk(CI, Builder);
+  case LibFunc_mempcpy_chk:
+    return optimizeMemPCpyChk(CI, Builder);
   case LibFunc_memmove_chk:
     return optimizeMemMoveChk(CI, Builder);
   case LibFunc_memset_chk:
Index: llvm/test/Transforms/InstCombine/fortify-folding.ll
===================================================================
--- llvm/test/Transforms/InstCombine/fortify-folding.ll
+++ llvm/test/Transforms/InstCombine/fortify-folding.ll
@@ -31,6 +31,28 @@
   ret i8* %ret
 }
 
+define i8* @test_mempcpy() {
+; CHECK-LABEL: @test_mempcpy(
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull align 1 dereferenceable(15) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull align 1 dereferenceable(15) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0), i64 15, i1 false)
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 15)
+;
+  %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0
+  %ret = call i8* @__mempcpy_chk(i8* %dst, i8* %src, i64 15, i64 -1)
+  ret i8* %ret
+}
+
+define i8* @test_not_mempcpy() {
+; CHECK-LABEL: @test_not_mempcpy(
+; CHECK-NEXT:    call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull align 1 dereferenceable(15) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i8* nonnull align 1 dereferenceable(15) getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0), i64 15, i1 false)
+; CHECK-NEXT:    ret i8* getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 15)
+;
+  %dst = getelementptr inbounds [60 x i8], [60 x i8]* @a, i32 0, i32 0
+  %src = getelementptr inbounds [60 x i8], [60 x i8]* @b, i32 0, i32 0
+  %ret = call i8* @__mempcpy_chk(i8* %dst, i8* %src, i64 15, i64 59)
+  ret i8* %ret
+}
+
 define i32 @test_snprintf() {
 ; CHECK-LABEL: @test_snprintf(
 ; CHECK-NEXT:    [[SNPRINTF:%.*]] = call i32 (i8*, i64, i8*, ...) @snprintf(i8* nonnull dereferenceable(1) getelementptr inbounds ([60 x i8], [60 x i8]* @a, i64 0, i64 0), i64 60, i8* getelementptr inbounds ([60 x i8], [60 x i8]* @b, i64 0, i64 0))
@@ -219,6 +241,7 @@
   ret i32 %ret
 }
 
+declare i8* @__mempcpy_chk(i8*, i8*, i64, i64)
 declare i8* @__memccpy_chk(i8*, i8*, i32, i64, i64)
 declare i32 @__snprintf_chk(i8*, i64, i32, i64, i8*, ...)
 declare i32 @__sprintf_chk(i8*, i32, i64, i8*, ...)