diff --git a/gfx/thebes/gfxDWriteFonts.cpp b/gfx/thebes/gfxDWriteFonts.cpp
index 2d1a39e3a6f..e31bfd4c97b 100644
--- a/gfx/thebes/gfxDWriteFonts.cpp
+++ b/gfx/thebes/gfxDWriteFonts.cpp
@@ -481,27 +481,37 @@ gfxDWriteFont::GetFontTable(PRUint32 aTag)
 }
 
 PRInt32
-gfxDWriteFont::GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
+gfxDWriteFont::GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
 {
     if (!mGlyphWidths.IsInitialized()) {
         mGlyphWidths.Init(200);
     }
 
-    PRInt32 width;
+    PRInt32 width = -1;
     if (mGlyphWidths.Get(aGID, &width)) {
         return width;
     }
 
     DWRITE_GLYPH_METRICS glyphMetrics;
-    HRESULT hr = mFontFace->GetGdiCompatibleGlyphMetrics(
+    HRESULT hr;
+    if (mUsingClearType) {
+        hr = mFontFace->GetDesignGlyphMetrics(
+                  &aGID, 1, &glyphMetrics, FALSE);
+        if (SUCCEEDED(hr)) {
+            width =
+                NS_lround(glyphMetrics.advanceWidth * mFUnitsConvFactor *
+                          65536.0);
+        }
+    } else {
+        hr = mFontFace->GetGdiCompatibleGlyphMetrics(
                   GetAdjustedSize(), 1.0f, nsnull, FALSE,
                   &aGID, 1, &glyphMetrics, FALSE);
-
-    if (NS_SUCCEEDED(hr)) {
-        width = NS_lround(glyphMetrics.advanceWidth * mFUnitsConvFactor) << 16;
-        mGlyphWidths.Put(aGID, width);
-        return width;
+        if (SUCCEEDED(hr)) {
+            width =
+                NS_lround(glyphMetrics.advanceWidth * mFUnitsConvFactor) << 16;
+        }
     }
 
-    return -1;
+    mGlyphWidths.Put(aGID, width);
+    return width;
 }
diff --git a/gfx/thebes/gfxDWriteFonts.h b/gfx/thebes/gfxDWriteFonts.h
index 9334caeac98..d382c1143b9 100644
--- a/gfx/thebes/gfxDWriteFonts.h
+++ b/gfx/thebes/gfxDWriteFonts.h
@@ -79,13 +79,16 @@ public:
     // use DWrite API to get direct access to system font data
     virtual hb_blob_t *GetFontTable(PRUint32 aTag);
 
-    virtual PRBool ProvidesHintedWidths() const {
-        return !mUsingClearType;
+    virtual PRBool ProvidesGlyphWidths() const {
+        return !mUsingClearType ||
+               (mFontFace->GetSimulations() & DWRITE_FONT_SIMULATIONS_BOLD);
     }
 
-    virtual PRInt32 GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
+    virtual PRInt32 GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
 
 protected:
+    friend class gfxDWriteShaper;
+
     virtual void CreatePlatformShaper();
 
     void ComputeMetrics();
diff --git a/gfx/thebes/gfxDWriteShaper.cpp b/gfx/thebes/gfxDWriteShaper.cpp
index 85654fa0a82..46ee2d75da9 100644
--- a/gfx/thebes/gfxDWriteShaper.cpp
+++ b/gfx/thebes/gfxDWriteShaper.cpp
@@ -175,7 +175,7 @@ trymoreglyphs:
             continue;
         }
 
-        if (mFont->ProvidesHintedWidths()) {
+        if (!static_cast<gfxDWriteFont*>(mFont)->mUsingClearType) {
             hr = analyzer->GetGdiCompatibleGlyphPlacements(
                                               aString + range.start,
                                               clusters.Elements(),
diff --git a/gfx/thebes/gfxFT2FontBase.cpp b/gfx/thebes/gfxFT2FontBase.cpp
index 53ada1cc686..269356c4f03 100644
--- a/gfx/thebes/gfxFT2FontBase.cpp
+++ b/gfx/thebes/gfxFT2FontBase.cpp
@@ -216,7 +216,7 @@ gfxFT2FontBase::GetGlyph(PRUint32 unicode, PRUint32 variation_selector)
 }
 
 PRInt32
-gfxFT2FontBase::GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
+gfxFT2FontBase::GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
 {
     cairo_text_extents_t extents;
     GetGlyphExtents(aGID, &extents);
diff --git a/gfx/thebes/gfxFT2FontBase.h b/gfx/thebes/gfxFT2FontBase.h
index 916efa389b8..3207a8d3121 100644
--- a/gfx/thebes/gfxFT2FontBase.h
+++ b/gfx/thebes/gfxFT2FontBase.h
@@ -63,8 +63,8 @@ public:
     virtual hb_blob_t *GetFontTable(PRUint32 aTag);
     virtual PRBool ProvidesGetGlyph() const { return PR_TRUE; }
     virtual PRUint32 GetGlyph(PRUint32 unicode, PRUint32 variation_selector);
-    virtual PRBool ProvidesHintedWidths() const { return PR_TRUE; }
-    virtual PRInt32 GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
+    virtual PRBool ProvidesGlyphWidths() const { return PR_TRUE; }
+    virtual PRInt32 GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
 
     cairo_scaled_font_t *CairoScaledFont() { return mScaledFont; };
     virtual PRBool SetupCairoFont(gfxContext *aContext);
diff --git a/gfx/thebes/gfxFont.h b/gfx/thebes/gfxFont.h
index eae828a8e9b..38477a7a99c 100644
--- a/gfx/thebes/gfxFont.h
+++ b/gfx/thebes/gfxFont.h
@@ -1009,16 +1009,16 @@ public:
         return 0;
     }
 
-    // subclasses may provide hinted glyph widths (in font units);
+    // subclasses may provide (possibly hinted) glyph widths (in font units);
     // if they do not override this, harfbuzz will use unhinted widths
     // derived from the font tables
-    virtual PRBool ProvidesHintedWidths() const {
+    virtual PRBool ProvidesGlyphWidths() const {
         return PR_FALSE;
     }
 
     // The return value is interpreted as a horizontal advance in 16.16 fixed
     // point format.
-    virtual PRInt32 GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID) {
+    virtual PRInt32 GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID) {
         return -1;
     }
 
diff --git a/gfx/thebes/gfxGDIFont.cpp b/gfx/thebes/gfxGDIFont.cpp
index ff7e84c4e7b..9012a9398c1 100644
--- a/gfx/thebes/gfxGDIFont.cpp
+++ b/gfx/thebes/gfxGDIFont.cpp
@@ -476,7 +476,7 @@ gfxGDIFont::FillLogFont(LOGFONTW& aLogFont, gfxFloat aSize)
 }
 
 PRInt32
-gfxGDIFont::GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
+gfxGDIFont::GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID)
 {
     if (!mGlyphWidths.IsInitialized()) {
         mGlyphWidths.Init(200);
diff --git a/gfx/thebes/gfxGDIFont.h b/gfx/thebes/gfxGDIFont.h
index 902785d5c87..aa0b706fadb 100644
--- a/gfx/thebes/gfxGDIFont.h
+++ b/gfx/thebes/gfxGDIFont.h
@@ -76,10 +76,10 @@ public:
     /* required for MathML to suppress effects of ClearType "padding" */
     virtual gfxFont* CopyWithAntialiasOption(AntialiasOption anAAOption);
 
-    virtual PRBool ProvidesHintedWidths() const { return PR_TRUE; }
+    virtual PRBool ProvidesGlyphWidths() const { return PR_TRUE; }
 
     // get hinted glyph width in pixels as 16.16 fixed-point value
-    virtual PRInt32 GetHintedGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
+    virtual PRInt32 GetGlyphWidth(gfxContext *aCtx, PRUint16 aGID);
 
 protected:
     virtual void CreatePlatformShaper();
diff --git a/gfx/thebes/gfxHarfBuzzShaper.cpp b/gfx/thebes/gfxHarfBuzzShaper.cpp
index a9eef1540cd..84fc12c2c7d 100644
--- a/gfx/thebes/gfxHarfBuzzShaper.cpp
+++ b/gfx/thebes/gfxHarfBuzzShaper.cpp
@@ -83,7 +83,7 @@ gfxHarfBuzzShaper::gfxHarfBuzzShaper(gfxFont *aFont)
       mSubtableOffset(0),
       mUVSTableOffset(0),
       mUseFontGetGlyph(aFont->ProvidesGetGlyph()),
-      mUseHintedWidths(aFont->ProvidesHintedWidths())
+      mUseFontGlyphWidths(aFont->ProvidesGlyphWidths())
 {
 }
 
@@ -215,8 +215,8 @@ gfxHarfBuzzShaper::GetGlyphAdvance(gfxContext *aContext,
                                    hb_position_t *x_advance,
                                    hb_position_t *y_advance) const
 {
-    if (mUseHintedWidths) {
-        *x_advance = mFont->GetHintedGlyphWidth(aContext, glyph);
+    if (mUseFontGlyphWidths) {
+        *x_advance = mFont->GetGlyphWidth(aContext, glyph);
         return;
     }
 
@@ -752,8 +752,8 @@ gfxHarfBuzzShaper::InitTextRun(gfxContext *aContext,
             hb_blob_unlock(mCmapTable);
         }
 
-        if (!mUseHintedWidths) {
-            // if font doesn't implement hinted widths, we will be reading
+        if (!mUseFontGlyphWidths) {
+            // if font doesn't implement GetGlyphWidth, we will be reading
             // the hmtx table directly;
             // read mNumLongMetrics from hhea table without caching its blob,
             // and preload/cache the hmtx table
@@ -788,7 +788,7 @@ gfxHarfBuzzShaper::InitTextRun(gfxContext *aContext,
     }
 
     if ((!mUseFontGetGlyph && mCmapFormat <= 0) ||
-        (!mUseHintedWidths && !mHmtxTable)) {
+        (!mUseFontGlyphWidths && !mHmtxTable)) {
         // unable to shape with this font
         return PR_FALSE;
     }
diff --git a/gfx/thebes/gfxHarfBuzzShaper.h b/gfx/thebes/gfxHarfBuzzShaper.h
index 665bdef0c3b..aaa4e2363bc 100644
--- a/gfx/thebes/gfxHarfBuzzShaper.h
+++ b/gfx/thebes/gfxHarfBuzzShaper.h
@@ -118,9 +118,9 @@ protected:
     // Whether the font implements GetGlyph, or we should read tables
     // directly
     PRPackedBool mUseFontGetGlyph;
-    // Whether the font implements hinted widths, or we should read tables
+    // Whether the font implements GetGlyphWidth, or we should read tables
     // directly to get ideal widths
-    PRPackedBool mUseHintedWidths;
+    PRPackedBool mUseFontGlyphWidths;
 };
 
 #endif /* GFX_HARFBUZZSHAPER_H */
diff --git a/layout/reftests/text/reftest.list b/layout/reftests/text/reftest.list
index d920bcc5fbe..5098efcc401 100644
--- a/layout/reftests/text/reftest.list
+++ b/layout/reftests/text/reftest.list
@@ -41,9 +41,7 @@ skip-if(!(d2d||cocoaWidget)) != subpixel-glyphs-x-2a.html subpixel-glyphs-x-2b.h
 == subpixel-glyphs-y-1a.html subpixel-glyphs-y-1b.html
 == subpixel-lineheight-1a.html subpixel-lineheight-1b.html
 == swash-1.html swash-1-ref.html
-# Test for bug 593564, synthetic bold should cause glyph metrics to increase
-# Random on Windows - fails on tinderbox Opt reftest, passes elsewhere - see bug 597300
-random-if(winWidget) HTTP(..) != synthetic-bold-metrics-01.html synthetic-bold-metrics-01-notref.html
+HTTP(..) != synthetic-bold-metrics-01.html synthetic-bold-metrics-01-notref.html
 == variation-selector-unsupported-1.html variation-selector-unsupported-1-ref.html
 == white-space-1a.html white-space-1-ref.html
 == white-space-1b.html white-space-1-ref.html