--- a/gfx/thebes/gfxFT2Fonts.cpp
+++ b/gfx/thebes/gfxFT2Fonts.cpp
@@ -60,17 +60,17 @@ gfxFT2Font::ShapeText(gfxContext      *a
                 mGraphiteShaper = new gfxGraphiteShaper(this);
             }
             ok = mGraphiteShaper->ShapeText(aContext, aText,
                                             aOffset, aLength,
                                             aScript, aShapedText);
         }
     }
 
-    if (!ok && gfxPlatform::GetPlatform()->UseHarfBuzzForScript(aScript)) {
+    if (!ok) {
         if (!mHarfBuzzShaper) {
             mHarfBuzzShaper = new gfxHarfBuzzShaper(this);
         }
         ok = mHarfBuzzShaper->ShapeText(aContext, aText,
                                         aOffset, aLength,
                                         aScript, aShapedText);
     }
 

--- a/gfx/thebes/gfxFont.cpp
+++ b/gfx/thebes/gfxFont.cpp
@@ -3965,20 +3965,18 @@ gfxFont::ShapeText(gfxContext      *aCon
     bool ok = false;
 
     if (mGraphiteShaper && gfxPlatform::GetPlatform()->UseGraphiteShaping()) {
         ok = mGraphiteShaper->ShapeText(aContext, aText, aOffset, aLength,
                                         aScript, aShapedText);
     }
 
     if (!ok && mHarfBuzzShaper && !aPreferPlatformShaping) {
-        if (gfxPlatform::GetPlatform()->UseHarfBuzzForScript(aScript)) {
-            ok = mHarfBuzzShaper->ShapeText(aContext, aText, aOffset, aLength,
-                                            aScript, aShapedText);
-        }
+        ok = mHarfBuzzShaper->ShapeText(aContext, aText, aOffset, aLength,
+                                        aScript, aShapedText);
     }
 
     if (!ok) {
         if (!mPlatformShaper) {
             CreatePlatformShaper();
         }
         if (mPlatformShaper) {
             ok = mPlatformShaper->ShapeText(aContext, aText, aOffset, aLength,

--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -138,18 +138,16 @@ public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSIOBSERVER
 };
 
 NS_IMPL_ISUPPORTS(SRGBOverrideObserver, nsIObserver, nsISupportsWeakReference)
 
 #define GFX_DOWNLOADABLE_FONTS_ENABLED "gfx.downloadable_fonts.enabled"
 
-#define GFX_PREF_HARFBUZZ_SCRIPTS "gfx.font_rendering.harfbuzz.scripts"
-#define HARFBUZZ_SCRIPTS_DEFAULT  mozilla::unicode::SHAPING_DEFAULT
 #define GFX_PREF_FALLBACK_USE_CMAPS  "gfx.font_rendering.fallback.always_use_cmaps"
 
 #define GFX_PREF_OPENTYPE_SVG "gfx.font_rendering.opentype_svg.enabled"
 
 #define GFX_PREF_WORD_CACHE_CHARLIMIT "gfx.font_rendering.wordcache.charlimit"
 #define GFX_PREF_WORD_CACHE_MAXENTRIES "gfx.font_rendering.wordcache.maxentries"
 
 #define GFX_PREF_GRAPHITE_SHAPING "gfx.font_rendering.graphite.enabled"
@@ -257,17 +255,16 @@ static const char *gPrefLangNames[] = {
     "x-tibt",
     "x-unicode",
 };
 
 gfxPlatform::gfxPlatform()
   : mAzureCanvasBackendCollector(MOZ_THIS_IN_INITIALIZER_LIST(),
                                  &gfxPlatform::GetAzureBackendInfo)
 {
-    mUseHarfBuzzScripts = UNINITIALIZED_VALUE;
     mAllowDownloadableFonts = UNINITIALIZED_VALUE;
     mFallbackUsesCmaps = UNINITIALIZED_VALUE;
 
     mWordCacheCharLimit = UNINITIALIZED_VALUE;
     mWordCacheMaxEntries = UNINITIALIZED_VALUE;
     mGraphiteShapingEnabled = UNINITIALIZED_VALUE;
     mOpenTypeSVGEnabled = UNINITIALIZED_VALUE;
     mBidiNumeralOption = UNINITIALIZED_VALUE;
@@ -1118,28 +1115,16 @@ gfxPlatform::UseGraphiteShaping()
     if (mGraphiteShapingEnabled == UNINITIALIZED_VALUE) {
         mGraphiteShapingEnabled =
             Preferences::GetBool(GFX_PREF_GRAPHITE_SHAPING, false);
     }
 
     return mGraphiteShapingEnabled;
 }
 
-bool
-gfxPlatform::UseHarfBuzzForScript(int32_t aScriptCode)
-{
-    if (mUseHarfBuzzScripts == UNINITIALIZED_VALUE) {
-        mUseHarfBuzzScripts = Preferences::GetInt(GFX_PREF_HARFBUZZ_SCRIPTS, HARFBUZZ_SCRIPTS_DEFAULT);
-    }
-
-    int32_t shapingType = mozilla::unicode::ScriptShapingType(aScriptCode);
-
-    return (mUseHarfBuzzScripts & shapingType) != 0;
-}
-
 gfxFontEntry*
 gfxPlatform::MakePlatformFont(const gfxProxyFontEntry *aProxyEntry,
                               const uint8_t *aFontData,
                               uint32_t aLength)
 {
     // Default implementation does not handle activating downloaded fonts;
     // just free the data and return.
     // Platforms that support @font-face must override this,
@@ -1863,19 +1848,16 @@ gfxPlatform::FontsPrefsChanged(const cha
         mWordCacheCharLimit = UNINITIALIZED_VALUE;
         FlushFontAndWordCaches();
     } else if (!strcmp(GFX_PREF_WORD_CACHE_MAXENTRIES, aPref)) {
         mWordCacheMaxEntries = UNINITIALIZED_VALUE;
         FlushFontAndWordCaches();
     } else if (!strcmp(GFX_PREF_GRAPHITE_SHAPING, aPref)) {
         mGraphiteShapingEnabled = UNINITIALIZED_VALUE;
         FlushFontAndWordCaches();
-    } else if (!strcmp(GFX_PREF_HARFBUZZ_SCRIPTS, aPref)) {
-        mUseHarfBuzzScripts = UNINITIALIZED_VALUE;
-        FlushFontAndWordCaches();
     } else if (!strcmp(BIDI_NUMERAL_PREF, aPref)) {
         mBidiNumeralOption = UNINITIALIZED_VALUE;
     } else if (!strcmp(GFX_PREF_OPENTYPE_SVG, aPref)) {
         mOpenTypeSVGEnabled = UNINITIALIZED_VALUE;
         gfxFontCache::GetCache()->AgeAllGenerations();
     }
 }
 

--- a/gfx/thebes/gfxPlatform.h
+++ b/gfx/thebes/gfxPlatform.h
@@ -402,23 +402,16 @@ public:
     uint32_t WordCacheMaxEntries();
 
     /**
      * Whether to use the SIL Graphite rendering engine
      * (for fonts that include Graphite tables)
      */
     bool UseGraphiteShaping();
 
-    /**
-     * Whether to use the harfbuzz shaper (depending on script complexity).
-     *
-     * This allows harfbuzz to be enabled selectively via the preferences.
-     */
-    bool UseHarfBuzzForScript(int32_t aScriptCode);
-
     // check whether format is supported on a platform or not (if unclear, returns true)
     virtual bool IsFontFormatSupported(nsIURI *aFontURI, uint32_t aFormatFlags) { return false; }
 
     void GetPrefFonts(nsIAtom *aLanguage, nsString& array, bool aAppendUnicode = true);
 
     // in some situations, need to make decisions about ambiguous characters, may need to look at multiple pref langs
     void GetLangPrefs(eFontPrefLang aPrefLangs[], uint32_t &aLen, eFontPrefLang aCharLang, eFontPrefLang aPageLang);
     
@@ -636,19 +629,16 @@ protected:
     int8_t  mOpenTypeSVGEnabled;
 
     int8_t  mBidiNumeralOption;
 
     // whether to always search font cmaps globally 
     // when doing system font fallback
     int8_t  mFallbackUsesCmaps;
 
-    // which scripts should be shaped with harfbuzz
-    int32_t mUseHarfBuzzScripts;
-
     // max character limit for words in word cache
     int32_t mWordCacheCharLimit;
 
     // max number of entries in word cache
     int32_t mWordCacheMaxEntries;
 
 private:
     /**

--- a/intl/unicharutil/util/nsUnicodeProperties.cpp
+++ b/intl/unicharutil/util/nsUnicodeProperties.cpp
@@ -244,74 +244,16 @@ bool
 IsClusterExtender(uint32_t aCh, uint8_t aCategory)
 {
     return ((aCategory >= HB_UNICODE_GENERAL_CATEGORY_SPACING_MARK &&
              aCategory <= HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) ||
             (aCh >= 0x200c && aCh <= 0x200d) || // ZWJ, ZWNJ
             (aCh >= 0xff9e && aCh <= 0xff9f));  // katakana sound marks
 }
 
-// TODO: replace this with a properties file or similar;
-// expect this to evolve as harfbuzz shaping support matures.
-//
-// The "shaping type" of each script run, as returned by this
-// function, is compared to the bits set in the
-// gfx.font_rendering.harfbuzz.scripts
-// preference to decide whether to use the harfbuzz shaper.
-//
-int32_t
-ScriptShapingType(int32_t aScriptCode)
-{
-    switch (aScriptCode) {
-    default:
-        return SHAPING_DEFAULT; // scripts not explicitly listed here are
-                                // assumed to just use default shaping
-
-    case MOZ_SCRIPT_ARABIC:
-    case MOZ_SCRIPT_SYRIAC:
-    case MOZ_SCRIPT_NKO:
-    case MOZ_SCRIPT_MANDAIC:
-        return SHAPING_ARABIC; // bidi scripts with Arabic-style shaping
-
-    case MOZ_SCRIPT_HEBREW:
-        return SHAPING_HEBREW;
-
-    case MOZ_SCRIPT_HANGUL:
-        return SHAPING_HANGUL;
-
-    case MOZ_SCRIPT_MONGOLIAN: // to be supported by the Arabic shaper?
-        return SHAPING_MONGOLIAN;
-
-    case MOZ_SCRIPT_THAI: // no complex OT features, but MS engines like to do
-                          // sequence checking
-        return SHAPING_THAI;
-
-    case MOZ_SCRIPT_BENGALI:
-    case MOZ_SCRIPT_DEVANAGARI:
-    case MOZ_SCRIPT_GUJARATI:
-    case MOZ_SCRIPT_GURMUKHI:
-    case MOZ_SCRIPT_KANNADA:
-    case MOZ_SCRIPT_MALAYALAM:
-    case MOZ_SCRIPT_ORIYA:
-    case MOZ_SCRIPT_SINHALA:
-    case MOZ_SCRIPT_TAMIL:
-    case MOZ_SCRIPT_TELUGU:
-    case MOZ_SCRIPT_KHMER:
-    case MOZ_SCRIPT_LAO:
-    case MOZ_SCRIPT_TIBETAN:
-    case MOZ_SCRIPT_NEW_TAI_LUE:
-    case MOZ_SCRIPT_TAI_LE:
-    case MOZ_SCRIPT_MYANMAR:
-    case MOZ_SCRIPT_PHAGS_PA:
-    case MOZ_SCRIPT_BATAK:
-    case MOZ_SCRIPT_BRAHMI:
-        return SHAPING_INDIC; // scripts that require Indic or other "special" shaping
-    }
-}
-
 void
 ClusterIterator::Next()
 {
     if (AtEnd()) {
         NS_WARNING("ClusterIterator has already reached the end");
         return;
     }
 

--- a/intl/unicharutil/util/nsUnicodeProperties.h
+++ b/intl/unicharutil/util/nsUnicodeProperties.h
@@ -114,28 +114,16 @@ inline HSType GetHangulSyllableType(uint
 // Case mappings for the full Unicode range;
 // note that it may be worth testing for ASCII chars and taking
 // a separate fast-path before calling these, in perf-critical places
 uint32_t GetUppercase(uint32_t aCh);
 uint32_t GetLowercase(uint32_t aCh);
 uint32_t GetTitlecaseForLower(uint32_t aCh); // maps LC to titlecase, UC unchanged
 uint32_t GetTitlecaseForAll(uint32_t aCh); // maps both UC and LC to titlecase
 
-enum ShapingType {
-  SHAPING_DEFAULT   = 0x0001,
-  SHAPING_ARABIC    = 0x0002,
-  SHAPING_HEBREW    = 0x0004,
-  SHAPING_HANGUL    = 0x0008,
-  SHAPING_MONGOLIAN = 0x0010,
-  SHAPING_INDIC     = 0x0020,
-  SHAPING_THAI      = 0x0040
-};
-
-int32_t ScriptShapingType(int32_t aScriptCode);
-
 // A simple iterator for a string of char16_t codepoints that advances
 // by Unicode grapheme clusters
 class ClusterIterator
 {
 public:
     ClusterIterator(const char16_t* aText, uint32_t aLength)
         : mPos(aText), mLimit(aText + aLength)
 #ifdef DEBUG

--- a/layout/reftests/indic-shaping/reftest.list
+++ b/layout/reftests/indic-shaping/reftest.list
@@ -1,22 +1,22 @@
-skip-if(B2G) pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == devanagari-1a.html devanagari-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != devanagari-1b.html devanagari-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == devanagari-2.html devanagari-2-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != devanagari-3a.html devanagari-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == devanagari-3b.html devanagari-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != devanagari-4.html devanagari-4-notref.html
+skip-if(B2G) HTTP(..) == devanagari-1a.html devanagari-1-ref.html
+HTTP(..) != devanagari-1b.html devanagari-1-ref.html
+HTTP(..) == devanagari-2.html devanagari-2-ref.html
+HTTP(..) != devanagari-3a.html devanagari-3-ref.html
+HTTP(..) == devanagari-3b.html devanagari-3-ref.html
+HTTP(..) != devanagari-4.html devanagari-4-notref.html
 
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == gujarati-1a.html gujarati-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != gujarati-1b.html gujarati-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == gujarati-2.html gujarati-2-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != gujarati-3a.html gujarati-3-ref.html
-skip-if(B2G) pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == gujarati-3b.html gujarati-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != gujarati-4.html gujarati-4-notref.html
+HTTP(..) == gujarati-1a.html gujarati-1-ref.html
+HTTP(..) != gujarati-1b.html gujarati-1-ref.html
+HTTP(..) == gujarati-2.html gujarati-2-ref.html
+HTTP(..) != gujarati-3a.html gujarati-3-ref.html
+skip-if(B2G) HTTP(..) == gujarati-3b.html gujarati-3-ref.html
+HTTP(..) != gujarati-4.html gujarati-4-notref.html
 
-skip-if(B2G) pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == bengali-1a.html bengali-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-1b.html bengali-1-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-2a.html bengali-2-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-2b.html bengali-2-ref.html
-skip-if(B2G) pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) == bengali-3a.html bengali-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-3b.html bengali-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-3c.html bengali-3-ref.html
-pref(gfx.font_rendering.harfbuzz.scripts,-1) HTTP(..) != bengali-3c.html bengali-3b.html
+skip-if(B2G) HTTP(..) == bengali-1a.html bengali-1-ref.html
+HTTP(..) != bengali-1b.html bengali-1-ref.html
+HTTP(..) != bengali-2a.html bengali-2-ref.html
+HTTP(..) != bengali-2b.html bengali-2-ref.html
+skip-if(B2G) HTTP(..) == bengali-3a.html bengali-3-ref.html
+HTTP(..) != bengali-3b.html bengali-3-ref.html
+HTTP(..) != bengali-3c.html bengali-3-ref.html
+HTTP(..) != bengali-3c.html bengali-3b.html

--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -419,33 +419,16 @@ pref("gfx.font_rendering.fallback.always
 // cache shaped word results
 pref("gfx.font_rendering.wordcache.charlimit", 32);
 
 // cache shaped word results
 pref("gfx.font_rendering.wordcache.maxentries", 10000);
 
 pref("gfx.font_rendering.graphite.enabled", true);
 
-// Check intl/unicharutil/util/nsUnicodeProperties.h for definitions of script bits
-// in the ShapingType enumeration
-// Currently-defined bits:
-//  SHAPING_DEFAULT   = 0x0001,
-//  SHAPING_ARABIC    = 0x0002,
-//  SHAPING_HEBREW    = 0x0004,
-//  SHAPING_HANGUL    = 0x0008,
-//  SHAPING_MONGOLIAN = 0x0010,
-//  SHAPING_INDIC     = 0x0020,
-//  SHAPING_THAI      = 0x0040
-// (see http://mxr.mozilla.org/mozilla-central/ident?i=ShapingType)
-// Scripts not listed are grouped in the default category.
-// Set the pref to 255 to have all text shaped via the harfbuzz backend.
-// Default setting:
-// We use harfbuzz for all scripts (except when using AAT fonts on OS X).
-pref("gfx.font_rendering.harfbuzz.scripts", 255);
-
 #ifdef XP_WIN
 pref("gfx.font_rendering.directwrite.enabled", false);
 pref("gfx.font_rendering.directwrite.use_gdi_table_loading", true);
 #endif
 
 pref("gfx.font_rendering.opentype_svg.enabled", true);
 
 #ifdef XP_WIN