diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -2366,28 +2366,63 @@
 
 /// ------------------------ Will-Return Attributes ----------------------------
 
-// Helper function that checks whether a function has any cycle.
+// Helper function that checks for unbounded cycle which is either a loop
+// that does not have a maximal trip count or any other cycle.
 // TODO: Replace with more efficent code
-static bool containsCycle(Function &F) {
-  SmallPtrSet<BasicBlock *, 32> Visited;
-
-  // Traverse BB by dfs and check whether successor is already visited.
-  for (BasicBlock *BB : depth_first(&F)) {
-    Visited.insert(BB);
-    for (auto *SuccBB : successors(BB)) {
-      if (Visited.count(SuccBB))
+static bool containsUnboundedCycle(Function &F, Attributor &A) {
+  bool NoAnalysis = false;
+
+  ScalarEvolution *SE =
+      A.getInfoCache().getAnalysisResultForFunction<ScalarEvolutionAnalysis>(F);
+  LoopInfo *LI = A.getInfoCache().getAnalysisResultForFunction<LoopAnalysis>(F);
+
+  if (!LI || !SE)
+    NoAnalysis = true;
+
+  for (scc_iterator<Function *> It = scc_begin(&F), IE = scc_end(&F); It != IE;
+       ++It) {
+
+    bool SCCHasLoop = It.hasLoop();
+    if (!SCCHasLoop)
+      continue;
+    // When NoAnalysis available then check only if the SCC has loop or not.
+    if (NoAnalysis && SCCHasLoop)
+      return true;
+
+    const std::vector<BasicBlock *> &SCCBBs = *It;
+    Loop *L = LI->getLoopFor(SCCBBs.front());
+    // Check whether the current SCC is a loop or not.
+    if (!L)
+      return true;
+
+    // Get the outer most loop and compare the number of blocks of the SCC and
+    // the loop to check if the current SCC is a loop cycle or not.If a loop
+    // then we check whether it is a bounded loop or unbounded loop.
+
+    do {
+      if (L->getNumBlocks() > SCCBBs.size())
         return true;
-    }
+
+      if (L->getNumBlocks() == SCCBBs.size()) {
+        if (!SE->getSmallConstantMaxTripCount(L))
+          return true;
+        break;
+      }
+
+    } while ((L = L->getParentLoop()));
+
+    // Check if there is an outer SCC with no loop that is as big as the
+    // current SCC.
+    if (!L)
+      return true;
   }
   return false;
 }
 
 // Helper function that checks the function have a loop which might become an
-// endless loop
-// FIXME: Any cycle is regarded as endless loop for now.
-//        We have to allow some patterns.
-static bool containsPossiblyEndlessLoop(Function *F) {
-  return !F || !F->hasExactDefinition() || containsCycle(*F);
+// endless loop.
+static bool containsPossiblyEndlessLoop(Function *F, Attributor &A) {
+  return !F || !F->hasExactDefinition() || containsUnboundedCycle(*F, A);
 }
 
 struct AAWillReturnImpl : public AAWillReturn {
@@ -2398,7 +2433,7 @@
     AAWillReturn::initialize(A);
 
     Function *F = getAssociatedFunction();
-    if (containsPossiblyEndlessLoop(F))
+    if (containsPossiblyEndlessLoop(F, A))
       indicatePessimisticFixpoint();
   }
 
diff --git a/llvm/test/Transforms/Attributor/read_write_returned_arguments_scc.ll b/llvm/test/Transforms/Attributor/read_write_returned_arguments_scc.ll
--- a/llvm/test/Transforms/Attributor/read_write_returned_arguments_scc.ll
+++ b/llvm/test/Transforms/Attributor/read_write_returned_arguments_scc.ll
@@ -101,7 +101,7 @@
   ret i32* %retval.0
 }
 
-; CHECK: Function Attrs: argmemonly nofree norecurse nosync nounwind
+; CHECK: Function Attrs: argmemonly nofree norecurse nosync nounwind willreturn
 ; CHECK-NEXT: define i32* @external_sink_ret2_nrw(i32* nofree readnone %n0, i32* nocapture nofree readonly %r0, i32* nofree returned writeonly "no-capture-maybe-returned" %w0)
 define i32* @external_sink_ret2_nrw(i32* %n0, i32* %r0, i32* %w0) {
 entry:
@@ -160,6 +160,7 @@
 ;
 ; CHECK-NOT: attributes #
 ; CHECK: attributes #{{.*}} = { argmemonly nofree nosync nounwind }
-; CHECK: attributes #{{.*}} = { argmemonly nofree norecurse nosync nounwind }
+; CHECK: attributes #{{.*}} = { argmemonly nofree norecurse nosync nounwind willreturn }
 ; CHECK: attributes #{{.*}} = { nosync nounwind }
+; CHECK: attributes #{{.*}} = { norecurse nosync nounwind willreturn }
 ; CHECK-NOT: attributes #
diff --git a/llvm/test/Transforms/Attributor/willreturn.ll b/llvm/test/Transforms/Attributor/willreturn.ll
--- a/llvm/test/Transforms/Attributor/willreturn.ll
+++ b/llvm/test/Transforms/Attributor/willreturn.ll
@@ -87,9 +87,8 @@
 ;   return ans;
 ; }
 
-; FIXME: missing willreturn
-; ATTRIBUTOR_MODULE: Function Attrs: nofree noinline nosync nounwind readnone uwtable
-; ATTRIBUTOR_CGSCC: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable
+; ATTRIBUTOR_MODULE: Function Attrs: nofree noinline nosync nounwind readnone uwtable willreturn
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable willreturn
 ; ATTRIBUTOR-NEXT: define i32 @fact_loop(i32 %0) local_unnamed_addr
 define i32 @fact_loop(i32 %0) local_unnamed_addr #0 {
   %2 = icmp slt i32 %0, 1
@@ -296,7 +295,7 @@
 
 
 ; TEST 11 (positive case)
-; counstant trip count
+; constant trip count
 ; int loop_constant_trip_count(int*p){
 ;    int ans = 0;
 ;    for(int i = 0;i<10;i++){
@@ -305,9 +304,8 @@
 ;    return ans;
 ; }
 
-; FIXME: missing willreturn
-; ATTRIBUTOR_MODULE: Function Attrs: argmemonly nofree noinline nosync nounwind readonly uwtable
-; ATTRIBUTOR_CGSCC: Function Attrs: argmemonly nofree noinline norecurse nosync nounwind readonly uwtable
+; ATTRIBUTOR_MODULE: Function Attrs: argmemonly nofree noinline nosync nounwind readonly uwtable willreturn
+; ATTRIBUTOR_CGSCC: Function Attrs: argmemonly nofree noinline norecurse nosync nounwind readonly uwtable willreturn
 ; ATTRIBUTOR-NEXT: define i32 @loop_constant_trip_count(i32* nocapture nofree readonly %0)
 define i32 @loop_constant_trip_count(i32* nocapture readonly %0) #0 {
   br label %3
@@ -374,9 +372,8 @@
 ;  }
 
 
-; FIXME: missing willreturn
-; ATTRIBUTOR_MODULE: Function Attrs: argmemonly nofree noinline nosync nounwind readonly uwtable
-; ATTRIBUTOR_CGSCC: Function Attrs: argmemonly nofree noinline norecurse nosync nounwind readonly uwtable
+; ATTRIBUTOR_MODULE: Function Attrs: argmemonly nofree noinline nosync nounwind readonly uwtable willreturn
+; ATTRIBUTOR_CGSCC: Function Attrs: argmemonly nofree noinline norecurse nosync nounwind readonly uwtable willreturn
 ; ATTRIBUTOR-NEXT: define i32 @loop_trip_dec(i32 %0, i32* nocapture nofree readonly %1) local_unnamed_addr
 
 define i32 @loop_trip_dec(i32 %0, i32* nocapture readonly %1) local_unnamed_addr #0 {
@@ -434,9 +431,8 @@
   unreachable
 }
 
-; FIXME: missing willreturn
-; ATTRIBUTOR_MODULE: Function Attrs: nofree noinline nosync nounwind readnone uwtable
-; ATTRIBUTOR_CGSCC: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable
+; ATTRIBUTOR_MODULE: Function Attrs: nofree noinline nosync nounwind readnone uwtable willreturn
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree noinline norecurse nosync nounwind readnone uwtable willreturn
 ; ATTRIBUTOR-NEXT: define i32 @unreachable_exit_positive2(i32 %0)
 define i32 @unreachable_exit_positive2(i32) local_unnamed_addr #0 {
   %2 = icmp slt i32 %0, 1
@@ -504,5 +500,210 @@
 }
 
 
+; TEST 16 (negative case)
+; non loop SCC inside a bounded loop  
+; int non_loop_inside_loop(int n) {
+;   int ans = 0;
+;   for (int i = 0; i < n; i++) {
+;     while (1)
+;       ans++;
+;   }
+;   return ans;
+; }
+
+; ATTRIBUTOR_MODULE: Function Attrs:  nofree nosync nounwind readnone
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree norecurse nosync nounwind readnone
+; ATTRIBUTOR-NOT: willreturn
+; ATTRIBUTOR-NEXT: define i32 @non_loop_inside_loop(i32 %n)
+define i32 @non_loop_inside_loop(i32 %n) {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %cmp = icmp sgt i32 %n, 0
+  br i1 %cmp, label %for.body, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond
+  br label %for.end
+
+for.body:                                         ; preds = %for.cond
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.body, %for.body
+  br label %while.body
+
+while.body:                                       ; preds = %while.cond
+  br label %while.cond
+
+for.inc:                                          ; No predecessors!
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond.cleanup
+  ret i32 0
+}
+
+
+; TEST 17 (positive case)
+; int loop_inside_loop(int n) {
+;   int ans = 0;
+;   for (int i = 0; i < n; i++) {
+;     while (n--) {
+;       ans++;
+;     }
+;   }
+;   return ans;
+; }
+
+; ATTRIBUTOR_MODULE: Function Attrs:  nofree nosync nounwind readnone willreturn
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree norecurse nosync nounwind readnone willreturn
+; ATTRIBUTOR-NEXT: define i32 @loop_inside_loop(i32 %n)
+define i32 @loop_inside_loop(i32 %n) {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %i.0 = phi i32 [ 0, %entry ], [ %inc1, %for.inc ]
+  %ans.0 = phi i32 [ 0, %entry ], [ %tmp, %for.inc ]
+  %n.addr.0 = phi i32 [ %n, %entry ], [ -1, %for.inc ]
+  %cmp = icmp slt i32 %i.0, %n.addr.0
+  br i1 %cmp, label %for.body, label %for.cond.cleanup
+
+for.cond.cleanup:                                 ; preds = %for.cond
+  %ans.0.lcssa = phi i32 [ %ans.0, %for.cond ]
+  br label %for.end
+
+for.body:                                         ; preds = %for.cond
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.body, %for.body
+  br i1 true, label %while.end, label %while.body
+
+while.body:                                       ; preds = %while.cond
+  br label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %tmp = add i32 %n.addr.0, %ans.0
+  br label %for.inc
+
+for.inc:                                          ; preds = %while.end
+  %inc1 = add nuw nsw i32 %i.0, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond.cleanup
+  ret i32 %ans.0.lcssa
+}
+
+
+; TEST 18 (negative case)
+; int loop_inside_non_loop(int n) {
+;   int ans = 0;
+;   while (n++) {
+;     for (int i = 0; i < n; i++) {
+;       ans++;
+;     }
+;   }
+;   return ans;
+; }
+
+; ATTRIBUTOR_MODULE: Function Attrs:  nofree nosync nounwind readnone
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree norecurse nosync nounwind readnone
+; ATTRIBUTOR-NOT: willreturn
+; ATTRIBUTOR-NEXT: define i32 @loop_inside_non_loop(i32 %n)
+define i32 @loop_inside_non_loop(i32 %n) {
+entry:
+  br label %while.cond
+
+while.cond:                                       ; preds = %for.end, %entry
+  %ans.0 = phi i32 [ 0, %entry ], [ %tmp2, %for.end ]
+  %n.addr.0 = phi i32 [ %n, %entry ], [ %inc, %for.end ]
+  %tmp = icmp sgt i32 %n.addr.0, -1
+  %smax = select i1 %tmp, i32 %n.addr.0, i32 -1
+  %inc = add nsw i32 %n.addr.0, 1
+  %tobool = icmp eq i32 %n.addr.0, 0
+  br i1 %tobool, label %while.end, label %while.body
+
+while.body:                                       ; preds = %while.cond
+  %tmp1 = add i32 %ans.0, 1
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %while.body
+  br i1 true, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:                                 ; preds = %for.cond
+  %tmp2 = add i32 %tmp1, %smax
+  br label %for.end
+
+for.body:                                         ; preds = %for.cond
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond.cleanup
+  br label %while.cond
+
+while.end:                                        ; preds = %while.cond
+  %ans.0.lcssa = phi i32 [ %ans.0, %while.cond ]
+  ret i32 %ans.0.lcssa
+}
+
+
+; TEST 19 (negative case)
+; int non_loops_SCCs(int n) {
+;   int ans = 0;
+;   while (n--) {
+;     while (n--) {
+;       ans++;
+;     }
+;     while (n--) {
+;       ans++;
+;     }
+;   }
+;   return ans;
+; }
+
+; ATTRIBUTOR_MODULE: Function Attrs:  nofree nosync nounwind readnone
+; ATTRIBUTOR_CGSCC: Function Attrs: nofree norecurse nosync nounwind readnone
+; ATTRIBUTOR-NOT: willreturn
+; ATTRIBUTOR-NEXT: define i32 @non_loops_SCCs(i32 %n)
+define i32 @non_loops_SCCs(i32 %n) {
+entry:
+  br label %while.cond
+
+while.cond:                                       ; preds = %while.end10, %entry
+  %ans.0 = phi i32 [ 0, %entry ], [ %tmp1, %while.end10 ]
+  %n.addr.0 = phi i32 [ %n, %entry ], [ -1, %while.end10 ]
+  %tobool = icmp eq i32 %n.addr.0, 0
+  br i1 %tobool, label %while.end11, label %while.body
+
+while.body:                                       ; preds = %while.cond
+  br label %while.cond1
+
+while.cond1:                                      ; preds = %while.body4, %while.body
+  br i1 true, label %while.end, label %while.body4
+
+while.body4:                                      ; preds = %while.cond1
+  br label %while.cond1
+
+while.end:                                        ; preds = %while.cond1
+  %tmp = add i32 %n.addr.0, -2
+  br label %while.cond5
+
+while.cond5:                                      ; preds = %while.body8, %while.end
+  br i1 true, label %while.end10, label %while.body8
+
+while.body8:                                      ; preds = %while.cond5
+  br label %while.cond5
+
+while.end10:                                      ; preds = %while.cond5
+  %tmp1 = add i32 %tmp, %ans.0
+  br label %while.cond
+
+while.end11:                                      ; preds = %while.cond
+  %ans.0.lcssa = phi i32 [ %ans.0, %while.cond ]
+  ret i32 %ans.0.lcssa
+}
+
+
 attributes #0 = { nounwind uwtable noinline }
 attributes #1 = { uwtable noinline }