diff --git a/cmake/platforms/OSX.cmake b/cmake/platforms/OSX.cmake
--- a/cmake/platforms/OSX.cmake
+++ b/cmake/platforms/OSX.cmake
@@ -1,7 +1,7 @@
 # Copyright (c) 2017 The Bitcoin developers
 
 set(CMAKE_SYSTEM_NAME Darwin)
-set(TOOLCHAIN_PREFIX x86_64-apple-darwin11)
+set(TOOLCHAIN_PREFIX x86_64-apple-darwin14)
 
 # On OSX, we use clang by default.
 set(CMAKE_C_COMPILER clang)
@@ -10,7 +10,7 @@
 # On OSX we use various stuff from Apple's SDK.
 set(OSX_SDK_PATH "${CMAKE_CURRENT_SOURCE_DIR}/depends/SDKs/MacOSX10.11.sdk")
 set(CMAKE_OSX_SYSROOT ${OSX_SDK_PATH})
-set(CMAKE_OSX_DEPLOYMENT_TARGET 10.8)
+set(CMAKE_OSX_DEPLOYMENT_TARGET 10.10)
 
 # target environment on the build host system
 #   set 1st to dir with the cross compiler's C/C++ headers/libs
diff --git a/contrib/gitian-descriptors/gitian-osx.yml b/contrib/gitian-descriptors/gitian-osx.yml
--- a/contrib/gitian-descriptors/gitian-osx.yml
+++ b/contrib/gitian-descriptors/gitian-osx.yml
@@ -36,7 +36,7 @@
 - "MacOSX10.11.sdk.tar.gz"
 script: |
   WRAP_DIR=$HOME/wrapped
-  HOSTS="x86_64-apple-darwin11"
+  HOSTS="x86_64-apple-darwin14"
   CONFIGFLAGS="--enable-reduce-exports --disable-bench --disable-gui-tests GENISOIMAGE=$WRAP_DIR/genisoimage"
   FAKETIME_HOST_PROGS=""
   FAKETIME_PROGS="ar ranlib date dmg genisoimage"
diff --git a/depends/Makefile b/depends/Makefile
--- a/depends/Makefile
+++ b/depends/Makefile
@@ -170,7 +170,7 @@
 download-one: check-sources $(all_sources)
 
 download-osx:
-	@$(MAKE) -s HOST=x86_64-apple-darwin11 download-one
+	@$(MAKE) -s HOST=x86_64-apple-darwin14 download-one
 download-linux:
 	@$(MAKE) -s HOST=x86_64-unknown-linux-gnu download-one
 download-win:
diff --git a/depends/README.md b/depends/README.md
--- a/depends/README.md
+++ b/depends/README.md
@@ -22,7 +22,7 @@
 
 - `i686-w64-mingw32` for Win32
 - `x86_64-w64-mingw32` for Win64
-- `x86_64-apple-darwin11` for macOS
+- `x86_64-apple-darwin14` for macOS
 - `arm-linux-gnueabihf` for Linux ARM 32 bit
 - `aarch64-linux-gnu` for Linux ARM 64 bit
 
diff --git a/depends/hosts/darwin.mk b/depends/hosts/darwin.mk
--- a/depends/hosts/darwin.mk
+++ b/depends/hosts/darwin.mk
@@ -1,4 +1,4 @@
-OSX_MIN_VERSION=10.8
+OSX_MIN_VERSION=10.10
 OSX_SDK_VERSION=10.11
 OSX_SDK=$(SDK_PATH)/MacOSX$(OSX_SDK_VERSION).sdk
 LD64_VERSION=253.9
diff --git a/doc/release-notes.md b/doc/release-notes.md
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -3,3 +3,6 @@
   <https://download.bitcoinabc.org/0.20.1/>
 
 This release includes the following features and fixes:
+ - From 0.20.1 onwards macOS <10.10 is no longer supported.
+   0.20.1 is built using Qt 5.9.6, which doesn't support
+   versions of macOS older than 10.10.
diff --git a/share/qt/Info.plist.in b/share/qt/Info.plist.in
--- a/share/qt/Info.plist.in
+++ b/share/qt/Info.plist.in
@@ -3,7 +3,7 @@
 <plist version="0.9">
 <dict>
   <key>LSMinimumSystemVersion</key>
-  <string>10.8.0</string>
+  <string>10.10.0</string>
 
   <key>LSArchitecturePriority</key>
   <array>
diff --git a/src/compat/byteswap.h b/src/compat/byteswap.h
--- a/src/compat/byteswap.h
+++ b/src/compat/byteswap.h
@@ -15,7 +15,7 @@
 #include <byteswap.h>
 #endif
 
-#if defined(__APPLE__)
+#if defined(MAC_OSX)
 
 #if !defined(bswap_16)
 
@@ -59,6 +59,6 @@
 }
 #endif // HAVE_DECL_BSWAP64
 
-#endif // defined(__APPLE__)
+#endif // defined(MAC_OSX)
 
 #endif // BITCOIN_COMPAT_BYTESWAP_H
diff --git a/src/qt/bitcoin.cpp b/src/qt/bitcoin.cpp
--- a/src/qt/bitcoin.cpp
+++ b/src/qt/bitcoin.cpp
@@ -698,7 +698,6 @@
     // that set the app orgname and app name! If you move the above 3 lines
     // to elsewhere, take this call with you!
     MigrateSettings();
-    GUIUtil::SubstituteFonts(GetLangTerritory());
 
     /// 4. Initialization of translations, so that intro dialog is in user's
     /// language. Now that QSettings are accessible, initialize translations.
diff --git a/src/qt/guiutil.h b/src/qt/guiutil.h
--- a/src/qt/guiutil.h
+++ b/src/qt/guiutil.h
@@ -146,9 +146,6 @@
 // Open the config file
 bool openBitcoinConf();
 
-// Replace invalid default fonts with known good ones
-void SubstituteFonts(const QString &language);
-
 /** Qt event filter that intercepts ToolTipChange events, and replaces the
  * tooltip with a rich text representation if needed.  This assures that Qt can
  * word-wrap long tooltip messages. Tooltips longer than the provided size
@@ -261,20 +258,7 @@
     void mouseReleaseEvent(QMouseEvent *event) override;
 };
 
-#if defined(Q_OS_MAC)
-// workaround for Qt OSX Bug:
-// https://bugreports.qt-project.org/browse/QTBUG-15631
-// QProgressBar uses around 10% CPU even when app is in background
-class ProgressBar : public ClickableProgressBar {
-    bool event(QEvent *e) override {
-        return (e->type() != QEvent::StyleAnimationUpdate)
-                   ? QProgressBar::event(e)
-                   : false;
-    }
-};
-#else
 typedef ClickableProgressBar ProgressBar;
-#endif
 
 } // namespace GUIUtil
 
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -65,14 +65,6 @@
 // These Mac includes must be done in the global namespace
 #include <CoreFoundation/CoreFoundation.h>
 #include <CoreServices/CoreServices.h>
-
-extern double NSAppKitVersionNumber;
-#if !defined(NSAppKitVersionNumber10_8)
-#define NSAppKitVersionNumber10_8 1187
-#endif
-#if !defined(NSAppKitVersionNumber10_9)
-#define NSAppKitVersionNumber10_9 1265
-#endif
 #endif
 
 namespace GUIUtil {
@@ -406,48 +398,6 @@
         QUrl::fromLocalFile(boostPathToQString(pathConfig)));
 }
 
-void SubstituteFonts(const QString &language) {
-#if defined(Q_OS_MAC)
-// Background:
-// OSX's default font changed in 10.9 and Qt is unable to find it with its
-// usual fallback methods when building against the 10.7 sdk or lower.
-// The 10.8 SDK added a function to let it find the correct fallback font.
-// If this fallback is not properly loaded, some characters may fail to
-// render correctly.
-//
-// The same thing happened with 10.10. .Helvetica Neue DeskInterface is now
-// default.
-//
-// Solution: If building with the 10.7 SDK or lower and the user's platform
-// is 10.9 or higher at runtime, substitute the correct font. This needs to
-// happen before the QApplication is created.
-#if defined(MAC_OS_X_VERSION_MAX_ALLOWED) &&                                   \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_8
-    if (floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_8) {
-        if (floor(NSAppKitVersionNumber) <= NSAppKitVersionNumber10_9) {
-            /* On a 10.9 - 10.9.x system */
-            QFont::insertSubstitution(".Lucida Grande UI", "Lucida Grande");
-        } else {
-            /* 10.10 or later system */
-            if (language == "zh_CN" || language == "zh_TW" ||
-                language == "zh_HK") {
-                // traditional or simplified Chinese
-                QFont::insertSubstitution(".Helvetica Neue DeskInterface",
-                                          "Heiti SC");
-            } else if (language == "ja") {
-                // Japanese
-                QFont::insertSubstitution(".Helvetica Neue DeskInterface",
-                                          "Songti SC");
-            } else {
-                QFont::insertSubstitution(".Helvetica Neue DeskInterface",
-                                          "Lucida Grande");
-            }
-        }
-    }
-#endif
-#endif
-}
-
 ToolTipToRichTextFilter::ToolTipToRichTextFilter(int _size_threshold,
                                                  QObject *parent)
     : QObject(parent), size_threshold(_size_threshold) {}
diff --git a/src/util.cpp b/src/util.cpp
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -1108,7 +1108,7 @@
         LogPrintf("%s: fdatasync failed: %d\n", __func__, errno);
         return false;
     }
-#elif defined(__APPLE__) && defined(F_FULLFSYNC)
+#elif defined(MAC_OSX) && defined(F_FULLFSYNC)
     // Manpage says "value other than -1" is returned on success
     if (fcntl(fileno(file), F_FULLFSYNC, 0) == -1) {
         LogPrintf("%s: fcntl F_FULLFSYNC failed: %d\n", __func__, errno);