diff --git a/Test/baseResults/spv.noBuiltInLoc.vert.out b/Test/baseResults/spv.noBuiltInLoc.vert.out
new file mode 100644
index 00000000..3d980bf0
--- /dev/null
+++ b/Test/baseResults/spv.noBuiltInLoc.vert.out
@@ -0,0 +1,51 @@
+spv.noBuiltInLoc.vert
+// Module Version 10000
+// Generated by (magic number): 80001
+// Id's are bound by 23
+
+                              Capability Shader
+               1:             ExtInstImport  "GLSL.std.450"
+                              MemoryModel Logical GLSL450
+                              EntryPoint Vertex 4  "main" 9 11 18
+                              Source GLSL 450
+                              Name 4  "main"
+                              Name 9  "bar"
+                              Name 11  "foo"
+                              Name 16  "gl_PerVertex"
+                              MemberName 16(gl_PerVertex) 0  "gl_Position"
+                              MemberName 16(gl_PerVertex) 1  "gl_PointSize"
+                              MemberName 16(gl_PerVertex) 2  "gl_ClipDistance"
+                              MemberName 16(gl_PerVertex) 3  "gl_CullDistance"
+                              Name 18  ""
+                              Decorate 9(bar) Location 0
+                              Decorate 11(foo) Location 0
+                              MemberDecorate 16(gl_PerVertex) 0 BuiltIn Position
+                              MemberDecorate 16(gl_PerVertex) 1 BuiltIn PointSize
+                              MemberDecorate 16(gl_PerVertex) 2 BuiltIn ClipDistance
+                              MemberDecorate 16(gl_PerVertex) 3 BuiltIn CullDistance
+                              Decorate 16(gl_PerVertex) Block
+               2:             TypeVoid
+               3:             TypeFunction 2
+               6:             TypeFloat 32
+               7:             TypeVector 6(float) 4
+               8:             TypePointer Output 7(fvec4)
+          9(bar):      8(ptr) Variable Output
+              10:             TypePointer Input 7(fvec4)
+         11(foo):     10(ptr) Variable Input
+              13:             TypeInt 32 0
+              14:     13(int) Constant 1
+              15:             TypeArray 6(float) 14
+16(gl_PerVertex):             TypeStruct 7(fvec4) 6(float) 15 15
+              17:             TypePointer Output 16(gl_PerVertex)
+              18:     17(ptr) Variable Output
+              19:             TypeInt 32 1
+              20:     19(int) Constant 0
+         4(main):           2 Function None 3
+               5:             Label
+              12:    7(fvec4) Load 11(foo)
+                              Store 9(bar) 12
+              21:    7(fvec4) Load 11(foo)
+              22:      8(ptr) AccessChain 18 20
+                              Store 22 21
+                              Return
+                              FunctionEnd
diff --git a/Test/runtests b/Test/runtests
index 29a20833..2a8542f4 100755
--- a/Test/runtests
+++ b/Test/runtests
@@ -103,6 +103,8 @@ diff -b $BASEDIR/hlsl.multiDescriptorSet.frag.out $TARGETDIR/hlsl.multiDescripto
 echo Testing SPV no location
 $EXE -V -C spv.noLocation.vert > $TARGETDIR/spv.noLocation.vert.out
 diff -b $BASEDIR/spv.noLocation.vert.out $TARGETDIR/spv.noLocation.vert.out || HASERROR=1
+$EXE -H --aml spv.noBuiltInLoc.vert > $TARGETDIR/spv.noBuiltInLoc.vert.out
+diff -b $BASEDIR/spv.noBuiltInLoc.vert.out $TARGETDIR/spv.noBuiltInLoc.vert.out || HASERROR=1
 
 #
 # Testing debug information
diff --git a/Test/spv.noBuiltInLoc.vert b/Test/spv.noBuiltInLoc.vert
new file mode 100644
index 00000000..e7548927
--- /dev/null
+++ b/Test/spv.noBuiltInLoc.vert
@@ -0,0 +1,13 @@
+#version 450 core
+
+layout(location = 0)
+in  vec4 foo;
+
+layout(location = 0)
+out vec4 bar;
+
+void main()
+{
+    bar = foo;
+    gl_Position = foo;
+}
\ No newline at end of file
diff --git a/glslang/MachineIndependent/iomapper.cpp b/glslang/MachineIndependent/iomapper.cpp
index 88c9bd60..ea5f1611 100644
--- a/glslang/MachineIndependent/iomapper.cpp
+++ b/glslang/MachineIndependent/iomapper.cpp
@@ -413,9 +413,22 @@ struct TDefaultIoResolverBase : public glslang::TIoMapResolver
     }
     int resolveInOutLocation(EShLanguage /*stage*/, const char* /*name*/, const TType& type, bool /*is_live*/) override
     {
-        if (!doAutoLocationMapping || type.getQualifier().hasLocation())
+        // kick out of not doing this
+        if (!doAutoLocationMapping)
             return -1;
 
+        // no locations added if already present, or a built-in variable
+        if (type.getQualifier().hasLocation() || type.getQualifier().builtIn != EbvNone)
+            return -1;
+
+        // no locations on blocks of built-in variables
+        if (type.isStruct()) {
+            if (type.getStruct()->size() < 1)
+                return -1;
+            if ((*type.getStruct())[0].type->getQualifier().builtIn != EbvNone)
+                return -1;
+        }
+
         // Placeholder.
         // TODO: It would be nice to flesh this out using 
         // intermediate->computeTypeLocationSize(type), or functions that call it like