diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index a28ea7294c..a988c515ce 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -10832,6 +10832,17 @@
     <string>F32</string>
     <key>Value</key>
     <real>0.5</real>
+  </map>
+  <key>RenderDiffuseLuminanceScale</key>
+  <map>
+    <key>Comment</key>
+    <string>Luminance adjustment for diffuse surfaces to aid auto-exposure behavior</string>
+    <key>Persist</key>
+    <integer>0</integer>
+    <key>Type</key>
+    <string>F32</string>
+    <key>Value</key>
+    <real>0.5</real>
   </map>
     <key>RenderShaderLODThreshold</key>
     <map>
diff --git a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
index c8afacf9bb..95b2f80e06 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/luminanceF.glsl
@@ -34,6 +34,8 @@ in vec2 vary_fragcoord;
 
 uniform sampler2D diffuseRect;
 uniform sampler2D emissiveRect;
+uniform sampler2D normalMap;
+uniform float diffuse_luminance_scale;
 
 float lum(vec3 col)
 {
@@ -45,7 +47,21 @@ void main()
 {
     vec2 tc = vary_fragcoord*0.6+0.2;
     tc.y -= 0.1; // HACK - nudge exposure sample down a little bit to favor ground over sky
-    vec3 c = texture(diffuseRect, tc).rgb + texture(emissiveRect, tc).rgb;
+    vec3 c = texture(diffuseRect, tc).rgb;
+    
+    vec4  norm         = texture(normalMap, tc);
+
+    if (!GET_GBUFFER_FLAG(GBUFFER_FLAG_HAS_HDRI) &&
+        !GET_GBUFFER_FLAG(GBUFFER_FLAG_SKIP_ATMOS))
+    {
+        // Apply the diffuse luminance scale to objects but not the sky
+        // Prevents underexposing when looking at bright environments
+        // while still allowing for realistically bright skies.
+        c *= diffuse_luminance_scale;
+    }
+
+    c += texture(emissiveRect, tc).rgb;
+
     float L = lum(c);
     frag_color = vec4(max(L, 0.0));
 }
diff --git a/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
index d89377326e..1629ed91c8 100644
--- a/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
+++ b/indra/newview/app_settings/shaders/class1/deferred/postDeferredGammaCorrect.glsl
@@ -153,6 +153,15 @@ float noise(vec2 x) {
 
 //=============================
 
+void debugExposure(inout vec3 color)
+{
+    float exp_scale = texture(exposureMap, vec2(0.5,0.5)).r;
+    exp_scale *= 0.5;
+    if (abs(vary_fragcoord.y-exp_scale) < 0.01 && vary_fragcoord.x < 0.1)
+    {
+        color = vec3(1,0,0);
+    }
+}
 
 vec3 legacyGamma(vec3 color)
 {
@@ -181,7 +190,8 @@ void main()
     vec3 seed = (diff.rgb+vec3(1.0))*vec3(tc.xy, tc.x+tc.y);
     vec3 nz = vec3(noise(seed.rg), noise(seed.gb), noise(seed.rb));
     diff.rgb += nz*0.003;
-    
+
+    //debugExposure(diff.rgb);
     frag_color = max(diff, vec4(0));
 }
 
diff --git a/indra/newview/pipeline.cpp b/indra/newview/pipeline.cpp
index 7809129743..ef6e7c3994 100644
--- a/indra/newview/pipeline.cpp
+++ b/indra/newview/pipeline.cpp
@@ -6759,6 +6759,8 @@ void LLPipeline::generateLuminance(LLRenderTarget* src, LLRenderTarget* dst)
 
 		gLuminanceProgram.bind();
 
+        static LLCachedControl<F32> diffuse_luminance_scale(gSavedSettings, "RenderDiffuseLuminanceScale", 1.0f);
+
 		S32 channel = 0;
 		channel = gLuminanceProgram.enableTexture(LLShaderMgr::DEFERRED_DIFFUSE);
 		if (channel > -1)
@@ -6772,6 +6774,16 @@ void LLPipeline::generateLuminance(LLRenderTarget* src, LLRenderTarget* dst)
 			mGlow[1].bindTexture(0, channel);
 		}
 
+        channel = gLuminanceProgram.enableTexture(LLShaderMgr::DEFERRED_NORMAL);
+        if (channel > -1)
+        {
+            // bind the normal map to get the environment mask
+            mRT->deferredScreen.bindTexture(2, channel, LLTexUnit::TFO_POINT);
+        }
+
+        static LLStaticHashedString diffuse_luminance_scale_s("diffuse_luminance_scale");
+        gLuminanceProgram.uniform1f(diffuse_luminance_scale_s, diffuse_luminance_scale);
+
 		mScreenTriangleVB->setBuffer();
 		mScreenTriangleVB->drawArrays(LLRender::TRIANGLES, 0, 3);
 		dst->flush();