diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -818,11 +818,10 @@
 
   if (ExplicitUnroll && TripCount != 0) {
     // If the loop has an unrolling pragma, we want to be more aggressive with
-    // unrolling limits. Set thresholds to at least the PragmaUnrollThreshold
-    // value which is larger than the default limits.
-    UP.Threshold = std::max<unsigned>(UP.Threshold, PragmaUnrollThreshold);
+    // unrolling limits. Double thresholds.
+    UP.Threshold = std::min<unsigned>(UP.Threshold * 2, PragmaUnrollThreshold);
     UP.PartialThreshold =
-        std::max<unsigned>(UP.PartialThreshold, PragmaUnrollThreshold);
+        std::min<unsigned>(UP.PartialThreshold * 2, PragmaUnrollThreshold);
   }
 
   // 3rd priority is full unroll count.
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-pragmas.ll b/llvm/test/Transforms/LoopUnroll/unroll-pragmas.ll
--- a/llvm/test/Transforms/LoopUnroll/unroll-pragmas.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-pragmas.ll
@@ -265,9 +265,9 @@
 ; #pragma clang loop unroll(enable)
 ; Loop should be fully unrolled.
 ;
-; CHECK-LABEL: @loop64_with_enable(
+; CHECK-LABEL: @loop32_with_enable(
 ; CHECK-NOT: br i1
-define void @loop64_with_enable(i32* nocapture %a) {
+define void @loop32_with_enable(i32* nocapture %a) {
 entry:
   br label %for.body
 
@@ -278,7 +278,7 @@
   %inc = add nsw i32 %0, 1
   store i32 %inc, i32* %arrayidx, align 4
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
-  %exitcond = icmp eq i64 %indvars.iv.next, 64
+  %exitcond = icmp eq i64 %indvars.iv.next, 32
   br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !13
 
 for.end:                                          ; preds = %for.body
@@ -287,6 +287,32 @@
 !13 = !{!13, !14}
 !14 = !{!"llvm.loop.unroll.enable"}
 
+; #pragma clang loop unroll(enable)
+; Partially unrolled with a count of 32.
+;
+; CHECK-LABEL: @loop64_with_enable(
+; CHECK:     %inc.31 = add nsw i32 %31, 1
+; CHECK-NOT: %inc.32
+define void @loop64_with_enable(i32* nocapture %a) {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
+  %0 = load i32, i32* %arrayidx, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* %arrayidx, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, 64
+  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !15
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+!15 = !{!15, !16}
+!16 = !{!"llvm.loop.unroll.enable"}
+
 ; #pragma clang loop unroll(enable)
 ; Loop has a runtime trip count and should be runtime unrolled and duplicated
 ; (original and 8x) if remainder is allowed, otherwise it should not be
@@ -324,12 +350,12 @@
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
   %lftr.wideiv = trunc i64 %indvars.iv.next to i32
   %exitcond = icmp eq i32 %lftr.wideiv, %b
-  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !15
+  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !17
 
 for.end:                                          ; preds = %for.body, %entry
   ret void
 }
-!15 = !{!15, !14}
+!17 = !{!17, !16}
 
 ; #pragma clang loop unroll_count(3)
 ; Loop has a runtime trip count.  Runtime unrolling should occur and loop
@@ -352,7 +378,7 @@
 define void @runtime_loop_with_count3(i32* nocapture %a, i32 %b) {
 entry:
   %cmp3 = icmp sgt i32 %b, 0
-  br i1 %cmp3, label %for.body, label %for.end, !llvm.loop !16
+  br i1 %cmp3, label %for.body, label %for.end, !llvm.loop !18
 
 for.body:                                         ; preds = %entry, %for.body
   %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
@@ -363,10 +389,10 @@
   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
   %lftr.wideiv = trunc i64 %indvars.iv.next to i32
   %exitcond = icmp eq i32 %lftr.wideiv, %b
-  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !16
+  br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !18
 
 for.end:                                          ; preds = %for.body, %entry
   ret void
 }
-!16 = !{!16, !17}
-!17 = !{!"llvm.loop.unroll.count", i32 3}
+!18 = !{!18, !19}
+!19 = !{!"llvm.loop.unroll.count", i32 3}