diff --git a/llvm/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll b/llvm/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
--- a/llvm/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
+++ b/llvm/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
@@ -1,54 +1,56 @@
-; RUN: opt -mtriple=x86_64-unknown-linux-gnu < %s -dfsan -S --dfsan-abilist=%S/Inputs/shadow-args-abilist.txt  | FileCheck %s
+; RUN: opt -mtriple=x86_64-unknown-linux-gnu < %s -dfsan -S --dfsan-abilist=%S/Inputs/shadow-args-abilist.txt | FileCheck %s
+; RUN: opt -mtriple=x86_64-unknown-linux-gnu < %s -dfsan -S --dfsan-abilist=%S/Inputs/shadow-args-abilist.txt -dfsan-fast-16-labels | FileCheck %s
 
 ; REQUIRES: x86-registered-target
 
 ; Test that the custom abi marks shadow parameters as zero extended.
 
+; CHECK: @__dfsan_shadow_width_bits = weak_odr constant i32 [[#SBITS:]]
+; CHECK: @__dfsan_shadow_width_bytes = weak_odr constant i32 [[#SBYTES:]]
+
 define i32 @m() {
+  ; CHECK-LABEL: @"dfs$m"
+  ; CHECK: %{{.*}} = call zeroext i16 @__dfsw_dfsan_get_label(i64 signext 56, i[[#SBITS]] zeroext 0, i[[#SBITS]]* %{{.*}})
+
 entry:
   %call = call zeroext i16 @dfsan_get_label(i64 signext 56)
   %conv = zext i16 %call to i32
   ret i32 %conv
 }
 
-; CHECK-LABEL: @"dfs$m"
-; CHECK: %{{.*}} = call zeroext i16 @__dfsw_dfsan_get_label(i64 signext 56, i16 zeroext 0, i16* %{{.*}})
-
 define i32 @k() {
+  ; CHECK-LABEL: @"dfs$k"
+  ; CHECK: %{{.*}} = call zeroext i16 @__dfsw_k2(i64 signext 56, i64 signext 67, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]]* %{{.*}})
+
 entry:
   %call = call zeroext i16 @k2(i64 signext 56, i64 signext 67)
   %conv = zext i16 %call to i32
   ret i32 %conv
 }
 
-; CHECK-LABEL: @"dfs$k"
-; CHECK: %{{.*}} = call zeroext i16 @__dfsw_k2(i64 signext 56, i64 signext 67, i16 zeroext {{.*}}, i16 zeroext {{.*}}, i16* %{{.*}})
-
 define i32 @k3() {
+  ; CHECK-LABEL: @"dfs$k3"
+  ; CHECK: %{{.*}} = call zeroext i16 @__dfsw_k4(i64 signext 56, i64 signext 67, i64 signext 78, i64 signext 89, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]] zeroext {{.*}}, i[[#SBITS]]* %{{.*}})
+
 entry:
   %call = call zeroext i16 @k4(i64 signext 56, i64 signext 67, i64 signext 78, i64 signext 89)
   %conv = zext i16 %call to i32
   ret i32 %conv
 }
 
-; CHECK-LABEL: @"dfs$k3"
-; CHECK: %{{.*}} = call zeroext i16 @__dfsw_k4(i64 signext 56, i64 signext 67, i64 signext 78, i64 signext 89, i16 zeroext {{.*}}, i16 zeroext {{.*}}, i16 zeroext {{.*}}, i16 zeroext {{.*}}, i16* %{{.*}})
-
 declare zeroext i16 @dfsan_get_label(i64 signext)
-
 ; CHECK-LABEL: @"dfsw$dfsan_get_label"
-; CHECK: %{{.*}} = call i16 @__dfsw_dfsan_get_label(i64 %0, i16 zeroext %1, i16* %{{.*}})
+; CHECK: %{{.*}} = call i16 @__dfsw_dfsan_get_label(i64 %0, i[[#SBITS]] zeroext %1, i[[#SBITS]]* %{{.*}})
 
 declare zeroext i16 @k2(i64 signext, i64 signext)
 ; CHECK-LABEL: @"dfsw$k2"
-; CHECK: %{{.*}} = call i16 @__dfsw_k2(i64 %{{.*}}, i64 %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16* %{{.*}})
+; CHECK: %{{.*}} = call i16 @__dfsw_k2(i64 %{{.*}}, i64 %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]]* %{{.*}})
 
 declare zeroext i16 @k4(i64 signext, i64 signext, i64 signext, i64 signext)
-
 ; CHECK-LABEL: @"dfsw$k4"
-; CHECK: %{{.*}} = call i16 @__dfsw_k4(i64 %{{.*}}, i64 %{{.*}}, i64  %{{.*}}, i64 %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16* %{{.*}})
+; CHECK: %{{.*}} = call i16 @__dfsw_k4(i64 %{{.*}}, i64 %{{.*}}, i64  %{{.*}}, i64 %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]] zeroext %{{.*}}, i[[#SBITS]]* %{{.*}})
 
 
-; CHECK: declare zeroext i16 @__dfsw_dfsan_get_label(i64 signext, i16, i16*)
-; CHECK: declare zeroext i16 @__dfsw_k2(i64 signext, i64 signext, i16, i16, i16*)
-; CHECK: declare zeroext i16 @__dfsw_k4(i64 signext, i64 signext, i64 signext, i64 signext, i16, i16, i16, i16, i16*)
+; CHECK: declare zeroext i16 @__dfsw_dfsan_get_label(i64 signext, i[[#SBITS]], i[[#SBITS]]*)
+; CHECK: declare zeroext i16 @__dfsw_k2(i64 signext, i64 signext, i[[#SBITS]], i[[#SBITS]], i[[#SBITS]]*)
+; CHECK: declare zeroext i16 @__dfsw_k4(i64 signext, i64 signext, i64 signext, i64 signext, i[[#SBITS]], i[[#SBITS]], i[[#SBITS]], i[[#SBITS]], i[[#SBITS]]*)