diff --git a/llvm/lib/ProfileData/SampleProf.cpp b/llvm/lib/ProfileData/SampleProf.cpp
--- a/llvm/lib/ProfileData/SampleProf.cpp
+++ b/llvm/lib/ProfileData/SampleProf.cpp
@@ -16,6 +16,7 @@
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/PseudoProbe.h"
 #include "llvm/ProfileData/SampleProfReader.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Error.h"
@@ -29,6 +30,11 @@
 using namespace llvm;
 using namespace sampleprof;
 
+static cl::opt<uint64_t> ProfileSymbolListCutOff(
+    "profile-symbol-list-cutoff", cl::Hidden, cl::init(-1), cl::ZeroOrMore,
+    cl::desc("Cutoff value about how many symbols in profile symbol list "
+             "will be used. This is very useful for performance debugging"));
+
 namespace llvm {
 namespace sampleprof {
 SampleProfileFormat FunctionSamples::Format;
@@ -274,12 +280,14 @@
                                         uint64_t ListSize) {
   const char *ListStart = reinterpret_cast<const char *>(Data);
   uint64_t Size = 0;
-  while (Size < ListSize) {
+  uint64_t StrNum = 0;
+  while (Size < ListSize && StrNum < ProfileSymbolListCutOff) {
     StringRef Str(ListStart + Size);
     add(Str);
     Size += Str.size() + 1;
+    StrNum++;
   }
-  if (Size != ListSize)
+  if (Size != ListSize && StrNum != ProfileSymbolListCutOff)
     return sampleprof_error::malformed;
   return sampleprof_error::success;
 }
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/profile-symbol-list.text b/llvm/test/Transforms/SampleProfile/Inputs/profile-symbol-list.text
--- a/llvm/test/Transforms/SampleProfile/Inputs/profile-symbol-list.text
+++ b/llvm/test/Transforms/SampleProfile/Inputs/profile-symbol-list.text
@@ -1,5 +1,6 @@
 _Z3goov
 _Z3sumii
+_Z3toov
 __libc_csu_fini
 __libc_csu_init
 _dl_relocate_static_pie
diff --git a/llvm/test/Transforms/SampleProfile/profile-sample-accurate.ll b/llvm/test/Transforms/SampleProfile/profile-sample-accurate.ll
--- a/llvm/test/Transforms/SampleProfile/profile-sample-accurate.ll
+++ b/llvm/test/Transforms/SampleProfile/profile-sample-accurate.ll
@@ -6,6 +6,8 @@
 ; RUN: llvm-profdata merge -sample -extbinary -prof-sym-list=%S/Inputs/profile-symbol-list.text %S/Inputs/profsampleacc.extbinary.afdo -o %t.symlist.afdo
 ; RUN: opt < %s -sample-profile -sample-profile-file=%t.symlist.afdo -profile-summary-cutoff-hot=600000 -profile-accurate-for-symsinlist -enable-new-pm=0 -S | FileCheck %s --check-prefix=PROFSYMLIST
 ; RUN: opt < %s -passes=sample-profile -sample-profile-file=%t.symlist.afdo -profile-summary-cutoff-hot=600000 -profile-accurate-for-symsinlist -S | FileCheck %s --check-prefix=PROFSYMLIST
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%t.symlist.afdo -profile-accurate-for-symsinlist -profile-symbol-list-cutoff=2 -S | FileCheck %s --check-prefix=PSLCUTOFF2
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%t.symlist.afdo -profile-accurate-for-symsinlist -profile-symbol-list-cutoff=3 -S | FileCheck %s --check-prefix=PSLCUTOFF3
 ;
 ; If -profile-accurate-for-symsinlist and -profile-sample-accurate both present,
 ; -profile-sample-accurate will override -profile-accurate-for-symsinlist.
@@ -60,6 +62,16 @@
   ret i32 %add, !dbg !11
 }
 
+; Check -profile-symbol-list-cutoff=3 will include _Z3toov into profile
+; symbol list and -profile-symbol-list-cutoff=2 will not.
+; PSLCUTOFF2: define i32 @_Z3toov{{.*}}!prof ![[TOO_ID:[0-9]+]]
+; PSLCUTOFF3: define i32 @_Z3toov{{.*}}!prof ![[TOO_ID:[0-9]+]]
+define i32 @_Z3toov(i32 %x, i32 %y) #0 {
+entry:
+  %add = add nsw i32 %x, %y
+  ret i32 %add
+}
+
 ; Function Attrs: uwtable
 define i32 @main() #0 !dbg !7 {
 entry:
@@ -132,6 +144,8 @@
 ; CALL_SUM_IS_HOT: ![[ZERO_ID]] = !{!"function_entry_count", i64 0}
 ; CALL_SUM_IS_WARM: ![[NONZERO_ID]] = !{!"function_entry_count", i64 5179}
 ; PROFSYMLIST: ![[UNKNOWN_ID]] = !{!"function_entry_count", i64 -1}
+; PSLCUTOFF2: ![[TOO_ID]] = !{!"function_entry_count", i64 -1}
+; PSLCUTOFF3: ![[TOO_ID]] = !{!"function_entry_count", i64 0}
 !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
 !1 = !DIFile(filename: "calls.cc", directory: ".")
 !2 = !{}