Index: llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -1470,6 +1470,7 @@
         }
 
         i = CS.arg_begin();
+        const unsigned ShadowArgStart = Args.size();
         for (unsigned n = FT->getNumParams(); n != 0; ++i, --n)
           Args.push_back(DFSF.getShadow(*i));
 
@@ -1505,6 +1506,15 @@
         CustomCI->setCallingConv(CI->getCallingConv());
         CustomCI->setAttributes(CI->getAttributes());
 
+        // Update the parameter attributes of the custom call instruction to
+        // zero extend the shadow parameters. This is required for targets
+        // which consider ShadowTy an illegal type.
+        for (unsigned n = 0; n < FT->getNumParams(); n++) {
+          const unsigned ArgNo = ShadowArgStart + n;
+          if (CustomCI->getArgOperand(ArgNo)->getType() == DFSF.DFS.ShadowTy)
+            CustomCI->addParamAttr(ArgNo, Attribute::ZExt);
+        }
+
         if (!FT->getReturnType()->isVoidTy()) {
           LoadInst *LabelLoad = IRB.CreateLoad(DFSF.LabelReturnAlloca);
           DFSF.setShadow(CustomCI, LabelLoad);
Index: llvm/trunk/test/Instrumentation/DataFlowSanitizer/Inputs/shadow-args-abilist.txt
===================================================================
--- llvm/trunk/test/Instrumentation/DataFlowSanitizer/Inputs/shadow-args-abilist.txt
+++ llvm/trunk/test/Instrumentation/DataFlowSanitizer/Inputs/shadow-args-abilist.txt
@@ -0,0 +1,8 @@
+fun:dfsan_get_label=uninstrumented
+fun:dfsan_get_label=custom
+
+fun:k2=uninstrumented
+fun:k2=custom
+
+fun:k4=uninstrumented
+fun:k4=custom
Index: llvm/trunk/test/Instrumentation/DataFlowSanitizer/abilist.ll
===================================================================
--- llvm/trunk/test/Instrumentation/DataFlowSanitizer/abilist.ll
+++ llvm/trunk/test/Instrumentation/DataFlowSanitizer/abilist.ll
@@ -47,13 +47,13 @@
   ; CHECK: %[[LABELVA1:.*]] = alloca [2 x i16]
   ; CHECK: %[[LABELRETURN:.*]] = alloca i16
 
-  ; CHECK: call void @__dfsw_custom1(i32 1, i32 2, i16 0, i16 0)
+  ; CHECK: call void @__dfsw_custom1(i32 1, i32 2, i16 zeroext 0, i16 zeroext 0)
   call void @custom1(i32 1, i32 2)
 
-  ; CHECK: call i32 @__dfsw_custom2(i32 1, i32 2, i16 0, i16 0, i16* %[[LABELRETURN]])
+  ; CHECK: call i32 @__dfsw_custom2(i32 1, i32 2, i16 zeroext 0, i16 zeroext 0, i16* %[[LABELRETURN]])
   call i32 @custom2(i32 1, i32 2)
 
-  ; CHECK: call void @__dfsw_customcb({{.*}} @"dfst0$customcb", i8* bitcast ({{.*}} @"dfs$cb" to i8*), i16 0)
+  ; CHECK: call void @__dfsw_customcb({{.*}} @"dfst0$customcb", i8* bitcast ({{.*}} @"dfs$cb" to i8*), i16 zeroext 0)
   call void @customcb(i32 (i32)* @cb)
 
   ; CHECK: %[[LABELVA1_0:.*]] = getelementptr inbounds [2 x i16], [2 x i16]* %[[LABELVA1]], i32 0, i32 0
@@ -61,12 +61,12 @@
   ; CHECK: %[[LABELVA1_1:.*]] = getelementptr inbounds [2 x i16], [2 x i16]* %[[LABELVA1]], i32 0, i32 1
   ; CHECK: store i16 %{{.*}}, i16* %[[LABELVA1_1]]
   ; CHECK: %[[LABELVA1_0A:.*]] = getelementptr inbounds [2 x i16], [2 x i16]* %[[LABELVA1]], i32 0, i32 0
-  ; CHECK: call void (i32, i16, i16*, ...) @__dfsw_custom3(i32 1, i16 0, i16* %[[LABELVA1_0A]], i32 2, i32 %{{.*}})
+  ; CHECK: call void (i32, i16, i16*, ...) @__dfsw_custom3(i32 1, i16 zeroext 0, i16* %[[LABELVA1_0A]], i32 2, i32 %{{.*}})
   call void (i32, ...) @custom3(i32 1, i32 2, i32 %x)
 
   ; CHECK: %[[LABELVA2_0:.*]] = getelementptr inbounds [2 x i16], [2 x i16]* %[[LABELVA2]], i32 0, i32 0
   ; CHECK: %[[LABELVA2_0A:.*]] = getelementptr inbounds [2 x i16], [2 x i16]* %[[LABELVA2]], i32 0, i32 0
-  ; CHECK: call i32 (i32, i16, i16*, i16*, ...) @__dfsw_custom4(i32 1, i16 0, i16* %[[LABELVA2_0A]], i16* %[[LABELRETURN]], i32 2, i32 3)
+  ; CHECK: call i32 (i32, i16, i16*, i16*, ...) @__dfsw_custom4(i32 1, i16 zeroext 0, i16* %[[LABELVA2_0A]], i16* %[[LABELRETURN]], i32 2, i32 3)
   call i32 (i32, ...) @custom4(i32 1, i32 2, i32 3)
 
   ret void
Index: llvm/trunk/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
===================================================================
--- llvm/trunk/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
+++ llvm/trunk/test/Instrumentation/DataFlowSanitizer/shadow-args-zext.ll
@@ -0,0 +1,54 @@
+; RUN: opt -mtriple=x86_64-unknown-linux-gnu < %s -dfsan -S --dfsan-abilist=%S/Inputs/shadow-args-abilist.txt  | FileCheck %s
+
+; REQUIRES: x86-registered-target
+
+; Test that the custom abi marks shadow parameters as zero extended.
+
+define i32 @m() {
+entry:
+  %call = call zeroext i16 @dfsan_get_label(i64 signext 56)
+  %conv = zext i16 %call to i32
+  ret i32 %conv
+}
+
+; CHECK-LABEL: @"dfs$m"
+; CHECK: %{{.*}} = call zeroext i16 @__dfsw_dfsan_get_label(i64 signext 56, i16 zeroext 0, i16* %{{.*}})
+
+define i32 @k() {
+entry:
+  %call = call zeroext i16 @k2(i64 signext 56, i64 signext 67)
+  %conv = zext i16 %call to i32
+  ret i32 %conv
+}
+
+; CHECK-LABEL: @"dfs$k"
+; CHECK: %{{.*}} = call zeroext i16 @__dfsw_k2(i64 signext 56, i64 signext 67, i16 zeroext {{.*}}, i16 zeroext {{.*}}, i16* %{{.*}})
+
+define i32 @k3() {
+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* %{{.*}})
+
+declare zeroext i16 @k2(i64 signext, i64 signext)
+; CHECK-LABEL: @"dfsw$k2"
+; CHECK: %{{.*}} = call i16 @__dfsw_k2(i64 %{{.*}}, i64 %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16* %{{.*}})
+
+declare zeroext i16 @k4(i64 signext, i64 signext, i64 signext, i64 signext)
+
+; CHECK-LABEL: @"dfsw$k4"
+; CHECK: %{{.*}} = call i16 @__dfsw_k4(i64 %{{.*}}, i64 %{{.*}}, i64  %{{.*}}, i64 %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16 zeroext %{{.*}}, i16* %{{.*}})
+
+
+; CHECK: 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*)