diff --git a/src/libs/botan/botan.pro b/src/libs/botan/botan.pro
index ed5542a6f27..0f2f18b1812 100644
--- a/src/libs/botan/botan.pro
+++ b/src/libs/botan/botan.pro
@@ -33,9 +33,14 @@ msvc: BOTAN_CXX_FLAGS += /wd4100 /wd4800 /wd4127 /wd4244 /wd4250 /wd4267 /wd4334
 else: BOTAN_CXX_FLAGS += -Wno-unused-parameter
 macos: BOTAN_CXX_FLAGS += -mmacosx-version-min=$$QMAKE_MACOSX_DEPLOYMENT_TARGET -isysroot $$shell_quote($$QMAKE_MAC_SDK_PATH)
 unix: BOTAN_CXX_FLAGS += -fPIC
-!isEmpty(BOTAN_CXX_FLAGS): OTHER_FLAGS += --cxxflags=$$shell_quote($$BOTAN_CXX_FLAGS)
 win32: OTHER_FLAGS += --link-method=hardlink
-CONFIG(debug, debug|release): OTHER_FLAGS += --debug-mode
+CONFIG(debug, debug|release) {
+    OTHER_FLAGS += --with-debug-info
+} else {
+    msvc: BOTAN_CXX_FLAGS += /O2
+    else: BOTAN_CXX_FLAGS += -O3
+}
+!isEmpty(BOTAN_CXX_FLAGS): OTHER_FLAGS += --cxxflags=$$shell_quote($$BOTAN_CXX_FLAGS)
 CONFIGURE_FILE_PATH_FOR_SHELL = $$shell_quote($$shell_path($$BOTAN_SOURCE_DIR/configure.py))
 
 configure_inputs = $$BOTAN_SOURCE_DIR/configure.py
diff --git a/src/libs/botan/botan.qbs b/src/libs/botan/botan.qbs
index e6a7369f368..004cdc2f2cd 100644
--- a/src/libs/botan/botan.qbs
+++ b/src/libs/botan/botan.qbs
@@ -42,7 +42,8 @@ Product {
                     + "sha2_32,sha2_32_x86,sha2_64,simd,system_rng,emsa_pkcs1,pbes2,pbkdf2";
             args.push("--enable-modules=" + modules);
             var cxxFlags = [];
-            if (product.qbs.toolchain.contains("msvc")) {
+            var tc = product.qbs.toolchain;
+            if (tc.contains("msvc")) {
                 cxxFlags.push("/wd4100", "/wd4800", "/wd4127", "/wd4244", "/wd4250", "/wd4267",
                               "/wd4334", "/wd4702", "/wd4996", "/D_ENABLE_EXTENDED_ALIGNED_STORAGE");
             }
@@ -55,10 +56,11 @@ Product {
             }
             if (product.qbs.targetOS.contains("unix"))
                 cxxFlags.push("-fPIC");
+            if (product.qbs.buildVariant === "release")
+                cxxFlags.push(tc.contains("msvc") ? "/O2" : "-O3");
             if (cxxFlags.length > 0)
                 args.push("--cxxflags=" + cxxFlags.join(" "));
             var ccOption = "--cc=";
-            var tc = product.qbs.toolchain;
             if (tc.contains("msvc"))
                 ccOption += "msvc";
             else if (tc.contains("clang"))