diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index e8e704408dc8e2..1f4f1c9abcebce 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -231,6 +231,15 @@ static bool setAlignedAllocParam(Function &F, unsigned ArgNo) {
   return true;
 }
 
+static bool setAllocSize(Function &F, unsigned ElemSizeArg,
+                         Optional<unsigned> NumElemsArg) {
+  if (F.hasFnAttribute(Attribute::AllocSize))
+    return false;
+  F.addFnAttr(Attribute::getWithAllocSizeArgs(F.getContext(), ElemSizeArg,
+                                              NumElemsArg));
+  return true;
+}
+
 bool llvm::inferLibFuncAttributes(Module *M, StringRef Name,
                                   const TargetLibraryInfo &TLI) {
   Function *F = M->getFunction(Name);
@@ -424,10 +433,12 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     return Changed;
   case LibFunc_aligned_alloc:
     Changed |= setAlignedAllocParam(F, 0);
+    Changed |= setAllocSize(F, 1, None);
     LLVM_FALLTHROUGH;
   case LibFunc_valloc:
   case LibFunc_malloc:
   case LibFunc_vec_malloc:
+    Changed |= setAllocSize(F, 0, None);
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
@@ -490,6 +501,7 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     Changed |= setOnlyReadsMemory(F, 1);
     return Changed;
   case LibFunc_memalign:
+    Changed |= setAllocSize(F, 1, None);
     Changed |= setAlignedAllocParam(F, 0);
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetNoUndef(F);
@@ -512,6 +524,7 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
   case LibFunc_realloc:
   case LibFunc_vec_realloc:
   case LibFunc_reallocf:
+    Changed |= setAllocSize(F, 1, None);
     Changed |= setOnlyAccessesInaccessibleMemOrArgMem(F);
     Changed |= setRetNoUndef(F);
     Changed |= setDoesNotThrow(F);
@@ -585,6 +598,7 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     return Changed;
   case LibFunc_calloc:
   case LibFunc_vec_calloc:
+    Changed |= setAllocSize(F, 0, 1);
     Changed |= setOnlyAccessesInaccessibleMemory(F);
     Changed |= setRetAndArgsNoUndef(F);
     Changed |= setDoesNotThrow(F);
diff --git a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
index 953798dbc00a33..950a8ce4bfe1a3 100644
--- a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
+++ b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
@@ -290,7 +290,7 @@ declare void @bcopy(i8*, i8*, i64)
 ; CHECK: declare void @bzero(i8* nocapture writeonly, i64)  [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
 declare void @bzero(i8*, i64)
 
-; CHECK: declare noalias noundef i8* @calloc(i64 noundef, i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN:#[0-9]+]]
+; CHECK: declare noalias noundef i8* @calloc(i64 noundef, i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN_ALLOCSIZE01:#[0-9]+]]
 declare i8* @calloc(i64, i64)
 
 ; CHECK: declare double @cbrt(double) [[NOFREE_NOUNWIND_WILLRETURN_WRITEONLY]]
@@ -656,7 +656,7 @@ declare i32 @lstat(i8*, %opaque*)
 ; CHECK-LINUX: declare noundef i32 @lstat64(i8* nocapture noundef readonly, %opaque* nocapture noundef) [[NOFREE_NOUNWIND]]
 declare i32 @lstat64(i8*, %opaque*)
 
-; CHECK: declare noalias noundef i8* @malloc(i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
+; CHECK: declare noalias noundef i8* @malloc(i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN_ALLOCSIZE:#[0-9]+]]
 declare i8* @malloc(i64)
 
 ; CHECK-LINUX: declare noalias noundef i8* @memalign(i64 allocalign, i64) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN:#[0-9]+]]
@@ -779,10 +779,10 @@ declare i64 @read(i32, i8*, i64)
 ; CHECK: declare noundef i64 @readlink(i8* nocapture noundef readonly, i8* nocapture noundef, i64 noundef) [[NOFREE_NOUNWIND]]
 declare i64 @readlink(i8*, i8*, i64)
 
-; CHECK: declare noalias noundef i8* @realloc(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]]
+; CHECK: declare noalias noundef i8* @realloc(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE:#[0-9]+]]
 declare i8* @realloc(i8*, i64)
 
-; CHECK: declare noalias noundef i8* @reallocf(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]]
+; CHECK: declare noalias noundef i8* @reallocf(i8* nocapture, i64 noundef) [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE]]
 declare i8* @reallocf(i8*, i64)
 
 ; CHECK: declare noundef i8* @realpath(i8* nocapture noundef readonly, i8* noundef) [[NOFREE_NOUNWIND]]
@@ -1031,7 +1031,7 @@ declare i32 @utime(i8*, %opaque*)
 ; CHECK: declare noundef i32 @utimes(i8* nocapture noundef readonly, %opaque* nocapture noundef readonly) [[NOFREE_NOUNWIND]]
 declare i32 @utimes(i8*, %opaque*)
 
-; CHECK: declare noalias noundef i8* @valloc(i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
+; CHECK: declare noalias noundef i8* @valloc(i64 noundef) [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN_ALLOCSIZE]]
 declare i8* @valloc(i64)
 
 ; CHECK: declare noundef i32 @vfprintf(%opaque* nocapture noundef, i8* nocapture noundef readonly, %opaque* noundef) [[NOFREE_NOUNWIND]]
@@ -1067,19 +1067,19 @@ declare void @memset_pattern8(i8*, i8*, i64)
 ; CHECK-DARWIN: declare void @memset_pattern16(i8* nocapture writeonly, i8* nocapture readonly, i64) [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]]
 declare void @memset_pattern16(i8*, i8*, i64)
 
-
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND_WILLRETURN]] = { mustprogress nofree nounwind willreturn }
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND_WILLRETURN_WRITEONLY]] = { mustprogress nofree nounwind willreturn writeonly }
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND]] = { nofree nounwind }
-; CHECK-DAG: attributes [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { inaccessiblememonly mustprogress nofree nounwind willreturn }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN_ALLOCSIZE]] = { inaccessiblememonly mustprogress nofree nounwind willreturn allocsize(0) }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN_ALLOCSIZE01]] = { inaccessiblememonly mustprogress nofree nounwind willreturn allocsize(0,1) }
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { mustprogress nofree nounwind readonly willreturn }
 ; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { argmemonly mustprogress nofree nounwind willreturn }
 ; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY]] = { nofree nounwind readonly }
 ; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly mustprogress nounwind willreturn }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN_ALLOCSIZE]] = { inaccessiblemem_or_argmemonly mustprogress nounwind willreturn allocsize(1) }
 ; CHECK-DAG: attributes [[NOFREE_WILLRETURN]] = { mustprogress nofree willreturn }
 ; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { argmemonly mustprogress nofree nounwind readonly willreturn }
 ; CHECK-DAG: attributes [[NOFREE]] = { nofree }
 ; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGONLY_NOFREE_NOUNWIND_WILLRETURN]]  = { inaccessiblemem_or_argmemonly mustprogress nofree nounwind willreturn }
 ; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND]] = { argmemonly nofree nounwind }
-
 ; CHECK-NVPTX-DAG: attributes [[NOFREE_NOUNWIND_READNONE]] = { nofree nosync nounwind readnone }