diff --git a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
--- a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
+++ b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp
@@ -153,6 +153,7 @@
 
     Changed |= deduplicateRuntimeCalls();
     Changed |= deleteParallelRegions();
+    Changed |= analysisConstantThreadNum();
 
     return Changed;
   }
@@ -384,6 +385,33 @@
     return Changed;
   }
 
+  bool analysisConstantThreadNum() {
+    for (Function *F : SCC) {
+      auto &RFI = RFIs[OMPRTL___kmpc_push_num_threads];
+      auto *UV = RFI.getUseVector(*F);
+      if (UV) {
+        for (Use *U : *UV) {
+          if (CallInst *CI = getCallIfRegularCall(*U, &RFI)) {
+            auto *Arg = CI->getArgOperand(RFI.getNumArgs() - 1);
+            if (ConstantInt *C = dyn_cast<ConstantInt>(Arg)) {
+
+              auto Remark = [&](OptimizationRemarkAnalysis ORA) {
+                return ORA << "Use of OpenMP parallel region with a constant ("
+                  << ore::NV("ConstantThreadNumber", C)
+                  << ") number of threads. ";
+              };
+              emitRemark<OptimizationRemarkAnalysis>(CI, 
+                  "OpenMPAnalysisConstantThreadCount", Remark);
+
+            }
+          }
+        }
+      }
+    }
+
+    return false;
+  }
+
   /// Collect arguments that represent the global thread id in \p GTIdArgs.
   void collectGlobalThreadIdArguments(SmallSetVector<Value *, 16> &GTIdArgs) {
     // TODO: Below we basically perform a fixpoint iteration with a pessimistic
diff --git a/llvm/test/Transforms/OpenMP/constant_thread_count_analysis.ll b/llvm/test/Transforms/OpenMP/constant_thread_count_analysis.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/OpenMP/constant_thread_count_analysis.ll
@@ -0,0 +1,119 @@
+; RUN: opt -openmpopt -pass-remarks-analysis=openmp-opt -disable-output < %s 2>&1 | FileCheck %s
+; RUN: opt -passes=openmpopt -pass-remarks-analysis=openmp-opt -disable-output < %s 2>&1 | FileCheck %s
+; ModuleID = 'constant_thread_count_analysis.ll'
+source_filename = "constant_thread_count_analysis.c"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux-gnu"
+
+%struct.ident_t = type { i32, i32, i32, i32, i8* }
+
+
+@.str = private unnamed_addr constant [23 x i8] c";unknown;unknown;0;0;;\00", align 1
+@0 = private unnamed_addr constant %struct.ident_t { i32 0, i32 2, i32 0, i32 0, i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i32 0, i32 0) }, align 8
+
+; CHECK: remark: constant_thread_count_analysis.c:6:5: Use of OpenMP parallel region with a constant (2) number of threads.
+define dso_local void @constant() local_unnamed_addr !dbg !13 {
+  %1 = call i32 @__kmpc_global_thread_num(%struct.ident_t* nonnull @0)
+  call void @__kmpc_push_num_threads(%struct.ident_t* nonnull @0, i32 %1, i32 2), !dbg !16
+  call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* nonnull @0, i32 0, void (i32*, i32*, ...)* bitcast (void (i32*, i32*)* @.omp_outlined. to void (i32*, i32*, ...)*)), !dbg !16
+  ret void, !dbg !17
+}
+
+define void @variable(i32 %0) local_unnamed_addr !dbg !18 {
+  %2 = call i32 @__kmpc_global_thread_num(%struct.ident_t* nonnull @0)
+  call void @__kmpc_push_num_threads(%struct.ident_t* nonnull @0, i32 %2, i32 %0), !dbg !24
+  call void (%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...) @__kmpc_fork_call(%struct.ident_t* nonnull @0, i32 0, void (i32*, i32*, ...)* bitcast (void (i32*, i32*)* @.omp_outlined..2 to void (i32*, i32*, ...)*)), !dbg !24
+  ret void, !dbg !25
+}
+
+define void @.omp_outlined._debug__() !dbg !26 {
+  call void (...) @do_work(), !dbg !36
+  ret void, !dbg !38
+}
+
+define void @.omp_outlined.(i32* %0, i32* %1) !dbg !39 {
+  call void @.omp_outlined._debug__(), !dbg !43
+  ret void, !dbg !43
+}
+
+define void @.omp_outlined._debug__.1() unnamed_addr !dbg !44 {
+  call void (...) @do_work(), !dbg !48
+  ret void, !dbg !50
+}
+
+define void @.omp_outlined..2(i32* noalias nocapture readnone %0, i32* noalias nocapture readnone %1) !dbg !51 {
+  call void @.omp_outlined._debug__.1(), !dbg !55
+  ret void, !dbg !55
+}
+
+declare !dbg !4 void @do_work(...)
+
+declare i32 @__kmpc_global_thread_num(%struct.ident_t*)
+
+declare void @__kmpc_push_num_threads(%struct.ident_t*, i32, i32)
+
+declare !callback !56 void @__kmpc_fork_call(%struct.ident_t*, i32, void (i32*, i32*, ...)*, ...)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8, !9, !10, !11}
+!llvm.ident = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "constant_thread_count_analysis.c", directory: "/tmp")
+!2 = !{}
+!3 = !{!4}
+!4 = !DISubprogram(name: "do_work", scope: !1, file: !1, line: 3, type: !5, spFlags: DISPFlagOptimized, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{null, null}
+!7 = !{i32 7, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{i32 7, !"PIC Level", i32 2}
+!11 = !{i32 7, !"PIE Level", i32 2}
+!12 = !{!"clang version 10.0.0 "}
+!13 = distinct !DISubprogram(name: "constant", scope: !1, file: !1, line: 5, type: !14, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!14 = !DISubroutineType(types: !15)
+!15 = !{null}
+!16 = !DILocation(line: 6, column: 5, scope: !13)
+!17 = !DILocation(line: 8, column: 1, scope: !13)
+!18 = distinct !DISubprogram(name: "variable", scope: !1, file: !1, line: 10, type: !19, scopeLine: 10, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !22)
+!19 = !DISubroutineType(types: !20)
+!20 = !{null, !21}
+!21 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!22 = !{!23}
+!23 = !DILocalVariable(name: "n", arg: 1, scope: !18, file: !1, line: 10, type: !21)
+!24 = !DILocation(line: 11, column: 5, scope: !18)
+!25 = !DILocation(line: 13, column: 1, scope: !18)
+!26 = distinct !DISubprogram(name: ".omp_outlined._debug__", scope: !1, file: !1, line: 7, type: !27, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !33)
+!27 = !DISubroutineType(types: !28)
+!28 = !{null, !29, !29}
+!29 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !30)
+!30 = !DIDerivedType(tag: DW_TAG_restrict_type, baseType: !31)
+!31 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !32, size: 64)
+!32 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !21)
+!33 = !{!34, !35}
+!34 = !DILocalVariable(name: ".global_tid.", arg: 1, scope: !26, type: !29, flags: DIFlagArtificial)
+!35 = !DILocalVariable(name: ".bound_tid.", arg: 2, scope: !26, type: !29, flags: DIFlagArtificial)
+!36 = !DILocation(line: 7, column: 7, scope: !37)
+!37 = distinct !DILexicalBlock(scope: !26, file: !1, line: 7, column: 5)
+!38 = !DILocation(line: 7, column: 18, scope: !26)
+!39 = distinct !DISubprogram(name: ".omp_outlined.", scope: !1, file: !1, line: 7, type: !27, scopeLine: 7, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !40)
+!40 = !{!41, !42}
+!41 = !DILocalVariable(name: ".global_tid.", arg: 1, scope: !39, type: !29, flags: DIFlagArtificial)
+!42 = !DILocalVariable(name: ".bound_tid.", arg: 2, scope: !39, type: !29, flags: DIFlagArtificial)
+!43 = !DILocation(line: 7, column: 5, scope: !39)
+!44 = distinct !DISubprogram(name: ".omp_outlined._debug__.1", scope: !1, file: !1, line: 12, type: !27, scopeLine: 12, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !45)
+!45 = !{!46, !47}
+!46 = !DILocalVariable(name: ".global_tid.", arg: 1, scope: !44, type: !29, flags: DIFlagArtificial)
+!47 = !DILocalVariable(name: ".bound_tid.", arg: 2, scope: !44, type: !29, flags: DIFlagArtificial)
+!48 = !DILocation(line: 12, column: 7, scope: !49)
+!49 = distinct !DILexicalBlock(scope: !44, file: !1, line: 12, column: 5)
+!50 = !DILocation(line: 12, column: 18, scope: !44)
+!51 = distinct !DISubprogram(name: ".omp_outlined..2", scope: !1, file: !1, line: 12, type: !27, scopeLine: 12, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !52)
+!52 = !{!53, !54}
+!53 = !DILocalVariable(name: ".global_tid.", arg: 1, scope: !51, type: !29, flags: DIFlagArtificial)
+!54 = !DILocalVariable(name: ".bound_tid.", arg: 2, scope: !51, type: !29, flags: DIFlagArtificial)
+!55 = !DILocation(line: 12, column: 5, scope: !51)
+!56 = !{!57}
+!57 = !{i64 2, i64 -1, i64 -1, i1 true}
+; ModuleID = 'constant_thread_count_analysis.ll'